Added `spaced_reference_links` extension.

This is now the default for pandoc's Markdown.
It allows whitespace between the two parts of a
reference link:  e.g.

    [a] [b]

    [b]: url

This is now forbidden by default.

Closes #2602.

1 files changed, 30 insertions, 72 deletions

diff --git a/test/writer.icml b/test/writer.icml
index b498f568b..c39915120 100644
--- a/test/writer.icml
+++ b/test/writer.icml
@@ -2566,37 +2566,9 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
 <Br />
 <ParagraphStyleRange AppliedParagraphStyle="ParagraphStyle/Paragraph">
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
-    <Content>Foo </Content>
-  </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-14" Name="" Hidden="false">
-    <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
-      <Content>bar</Content>
-    </CharacterStyleRange>
-  </HyperlinkTextSource>
-  <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
-    <Content>.</Content>
-  </CharacterStyleRange>
-</ParagraphStyleRange>
-<Br />
-<ParagraphStyleRange AppliedParagraphStyle="ParagraphStyle/Paragraph">
-  <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
-    <Content>Foo </Content>
-  </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-15" Name="" Hidden="false">
-    <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
-      <Content>bar</Content>
-    </CharacterStyleRange>
-  </HyperlinkTextSource>
-  <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
-    <Content>.</Content>
-  </CharacterStyleRange>
-</ParagraphStyleRange>
-<Br />
-<ParagraphStyleRange AppliedParagraphStyle="ParagraphStyle/Paragraph">
-  <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>With </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-16" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-14" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>embedded [brackets]</Content>
     </CharacterStyleRange>
@@ -2607,7 +2579,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
 </ParagraphStyleRange>
 <Br />
 <ParagraphStyleRange AppliedParagraphStyle="ParagraphStyle/Paragraph">
-  <HyperlinkTextSource Self="htss-17" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-15" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>b</Content>
     </CharacterStyleRange>
@@ -2621,7 +2593,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Indented </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-18" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-16" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>once</Content>
     </CharacterStyleRange>
@@ -2635,7 +2607,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Indented </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-19" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-17" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>twice</Content>
     </CharacterStyleRange>
@@ -2649,7 +2621,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Indented </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-20" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-18" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>thrice</Content>
     </CharacterStyleRange>
@@ -2675,7 +2647,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Foo </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-21" Name="Title with &quot;quotes&quot; inside" Hidden="false">
+  <HyperlinkTextSource Self="htss-19" Name="Title with &quot;quotes&quot; inside" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>bar</Content>
     </CharacterStyleRange>
@@ -2689,7 +2661,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Foo </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-22" Name="Title with &quot;quote&quot; inside" Hidden="false">
+  <HyperlinkTextSource Self="htss-20" Name="Title with &quot;quote&quot; inside" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>biz</Content>
     </CharacterStyleRange>
@@ -2709,7 +2681,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Here’s a </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-23" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-21" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>link with an ampersand in the URL</Content>
     </CharacterStyleRange>
@@ -2723,7 +2695,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Here’s a link with an amersand in the link text: </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-24" Name="AT&amp;T" Hidden="false">
+  <HyperlinkTextSource Self="htss-22" Name="AT&amp;T" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>AT&amp;T</Content>
     </CharacterStyleRange>
@@ -2737,7 +2709,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Here’s an </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-25" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-23" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>inline link</Content>
     </CharacterStyleRange>
@@ -2751,7 +2723,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Here’s an </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-26" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-24" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>inline link in pointy braces</Content>
     </CharacterStyleRange>
@@ -2771,7 +2743,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>With an ampersand: </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-27" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-25" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>http://example.com/?foo=1&amp;bar=2</Content>
     </CharacterStyleRange>
@@ -2785,7 +2757,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
 </ParagraphStyleRange>
 <Br />
 <ParagraphStyleRange AppliedParagraphStyle="ParagraphStyle/BulList">
-  <HyperlinkTextSource Self="htss-28" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-26" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>http://example.com/</Content>
     </CharacterStyleRange>
@@ -2802,7 +2774,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>An e-mail address: </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-29" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-27" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>nobody@nowhere.net</Content>
     </CharacterStyleRange>
@@ -2813,7 +2785,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
   <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
     <Content>Blockquoted: </Content>
   </CharacterStyleRange>
-  <HyperlinkTextSource Self="htss-30" Name="" Hidden="false">
+  <HyperlinkTextSource Self="htss-28" Name="" Hidden="false">
     <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
       <Content>http://example.com/</Content>
     </CharacterStyleRange>
@@ -3025,7 +2997,7 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
         <CharacterStyleRange AppliedCharacterStyle="$ID/NormalCharacterStyle">
           <Content> to type. Inline notes may contain </Content>
         </CharacterStyleRange>
-        <HyperlinkTextSource Self="htss-31" Name="" Hidden="false">
+        <HyperlinkTextSource Self="htss-29" Name="" Hidden="false">
           <CharacterStyleRange AppliedCharacterStyle="CharacterStyle/Link">
             <Content>links</Content>
           </CharacterStyleRange>
@@ -3098,118 +3070,104 @@ These should not be escaped:  \$ \\ \&gt; \[ \{</Content>
 
   </Story>
   <HyperlinkURLDestination Self="HyperlinkURLDestination/http%3a//google.com" Name="link" DestinationURL="http://google.com" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-31" Name="http://google.com" Source="htss-31" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-29" Name="http://google.com" Source="htss-29" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination/http%3a//google.com</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination/http%3a//example.com/" Name="link" DestinationURL="http://example.com/" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-30" Name="http://example.com/" Source="htss-30" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-28" Name="http://example.com/" Source="htss-28" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination/http%3a//example.com/</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination/mailto%3anobody@nowhere.net" Name="link" DestinationURL="mailto:nobody@nowhere.net" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-29" Name="mailto:nobody@nowhere.net" Source="htss-29" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-27" Name="mailto:nobody@nowhere.net" Source="htss-27" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination/mailto%3anobody@nowhere.net</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination/http%3a//example.com/" Name="link" DestinationURL="http://example.com/" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-28" Name="http://example.com/" Source="htss-28" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-26" Name="http://example.com/" Source="htss-26" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination/http%3a//example.com/</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination/http%3a//example.com/?foo=1&amp;bar=2" Name="link" DestinationURL="http://example.com/?foo=1&amp;bar=2" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-27" Name="http://example.com/?foo=1&amp;bar=2" Source="htss-27" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-25" Name="http://example.com/?foo=1&amp;bar=2" Source="htss-25" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination/http%3a//example.com/?foo=1&amp;bar=2</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination//script?foo=1&amp;bar=2" Name="link" DestinationURL="/script?foo=1&amp;bar=2" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-26" Name="/script?foo=1&amp;bar=2" Source="htss-26" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-24" Name="/script?foo=1&amp;bar=2" Source="htss-24" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination//script?foo=1&amp;bar=2</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination//script?foo=1&amp;bar=2" Name="link" DestinationURL="/script?foo=1&amp;bar=2" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-25" Name="/script?foo=1&amp;bar=2" Source="htss-25" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-23" Name="/script?foo=1&amp;bar=2" Source="htss-23" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination//script?foo=1&amp;bar=2</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination/http%3a//att.com/" Name="link" DestinationURL="http://att.com/" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-24" Name="http://att.com/" Source="htss-24" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-22" Name="http://att.com/" Source="htss-22" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination/http%3a//att.com/</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination/http%3a//example.com/?foo=1&amp;bar=2" Name="link" DestinationURL="http://example.com/?foo=1&amp;bar=2" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-23" Name="http://example.com/?foo=1&amp;bar=2" Source="htss-23" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-21" Name="http://example.com/?foo=1&amp;bar=2" Source="htss-21" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination/http%3a//example.com/?foo=1&amp;bar=2</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination//url/" Name="link" DestinationURL="/url/" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-22" Name="/url/" Source="htss-22" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-20" Name="/url/" Source="htss-20" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination//url/</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination//url/" Name="link" DestinationURL="/url/" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-21" Name="/url/" Source="htss-21" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-19" Name="/url/" Source="htss-19" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination//url/</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination//url" Name="link" DestinationURL="/url" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-20" Name="/url" Source="htss-20" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-18" Name="/url" Source="htss-18" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination//url</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination//url" Name="link" DestinationURL="/url" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-19" Name="/url" Source="htss-19" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-17" Name="/url" Source="htss-17" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination//url</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination//url" Name="link" DestinationURL="/url" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-18" Name="/url" Source="htss-18" Visible="true" DestinationUniqueKey="1">
+  <Hyperlink Self="uf-16" Name="/url" Source="htss-16" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>
       <Destination type="object">HyperlinkURLDestination//url</Destination>
     </Properties>
   </Hyperlink>
   <HyperlinkURLDestination Self="HyperlinkURLDestination//url/" Name="link" DestinationURL="/url/" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-17" Name="/url/" Source="htss-17" Visible="true" DestinationUniqueKey="1">
-    <Properties>
-      <BorderColor type="enumeration">Black</BorderColor>
-      <Destination type="object">HyperlinkURLDestination//url/</Destination>
-    </Properties>
-  </Hyperlink>
-  <HyperlinkURLDestination Self="HyperlinkURLDestination//url/" Name="link" DestinationURL="/url/" DestinationUniqueKey="1" />
-  <Hyperlink Self="uf-16" Name="/url/" Source="htss-16" Visible="true" DestinationUniqueKey="1">
-    <Properties>
-      <BorderColor type="enumeration">Black</BorderColor>
-      <Destination type="object">HyperlinkURLDestination//url/</Destination>
-    </Properties>
-  </Hyperlink>
-  <HyperlinkURLDestination Self="HyperlinkURLDestination//url/" Name="link" DestinationURL="/url/" DestinationUniqueKey="1" />
   <Hyperlink Self="uf-15" Name="/url/" Source="htss-15" Visible="true" DestinationUniqueKey="1">
     <Properties>
       <BorderColor type="enumeration">Black</BorderColor>