Replace Element and makeHierarchical with makeSections.

Text.Pandoc.Shared:

+ Remove `Element` type [API change]
+ Remove `makeHierarchicalize` [API change]
+ Add `makeSections` [API change]
+ Export `deLink` [API change]

Now that we have Divs, we can use them to represent the structure
of sections, and we don't need a special Element type.
`makeSections` reorganizes a block list, adding Divs with
class `section` around sections, and adding numbering
if needed.

This change also fixes some longstanding issues recognizing
section structure when the document contains Divs.
Closes #3057, see also #997.

All writers have been changed to use `makeSections`.
Note that in the process we have reverted the change
c1d058aeb1c6a331a2cc22786ffaab17f7118ccd
made in response to #5168, which I'm not completely
sure was a good idea.

Lua modules have also been adjusted accordingly.
Existing lua filters that use `hierarchicalize` will
need to be rewritten to use `make_sections`.

7 files changed, 7 insertions, 22 deletions

diff --git a/test/command/1710.md b/test/command/1710.md
index 4d9c64b30..64d86cffe 100644
--- a/test/command/1710.md
+++ b/test/command/1710.md
@@ -56,7 +56,6 @@ ok
 ^D
 \begin{frame}{Slide one}
 \protect\hypertarget{slide-one}{}
-
 \begin{columns}[T]
 \begin{column}{0.4\textwidth}
 \begin{itemize}
@@ -82,6 +81,5 @@ ok
 ok
 \end{column}
 \end{columns}
-
 \end{frame}
 ```
diff --git a/test/command/4016.md b/test/command/4016.md
index 5e4e35e0d..577ac1b09 100644
--- a/test/command/4016.md
+++ b/test/command/4016.md
@@ -15,32 +15,28 @@ pandoc -t beamer
 ^D
 \begin{frame}{Level 2 blocks}
 \protect\hypertarget{level-2-blocks}{}
-
 \begin{columns}[T]
 \begin{column}{0.4\textwidth}
 \begin{block}{Block one}
-
+\protect\hypertarget{block-one}{}
 \begin{itemize}
 \tightlist
 \item
   Item
 \end{itemize}
-
 \end{block}
 \end{column}
 
 \begin{column}{0.6\textwidth}
 \begin{block}{Block two}
-
+\protect\hypertarget{block-two}{}
 \begin{itemize}
 \tightlist
 \item
   Item
 \end{itemize}
-
 \end{block}
 \end{column}
 \end{columns}
-
 \end{frame}
 ```
diff --git a/test/command/4690.md b/test/command/4690.md
index deccfba13..9a46823cc 100644
--- a/test/command/4690.md
+++ b/test/command/4690.md
@@ -13,7 +13,6 @@ content2
 ^D
 \begin{frame}{title}
 \protect\hypertarget{title}{}
-
 \begin{columns}[T]
 \begin{column}{0.08\textwidth}
 content
@@ -23,6 +22,5 @@ content
 content2
 \end{column}
 \end{columns}
-
 \end{frame}
 ```
diff --git a/test/command/empty_paragraphs.md b/test/command/empty_paragraphs.md
index 001aaf1b0..14bd8d060 100644
--- a/test/command/empty_paragraphs.md
+++ b/test/command/empty_paragraphs.md
@@ -37,8 +37,6 @@
 [Para [Str "hi"], Para [], Para [], Para [Str "lo"]]
 ^D
 <p>hi</p>
-
-
 <p>lo</p>
 ```
 
diff --git a/test/lua/module/pandoc-utils.lua b/test/lua/module/pandoc-utils.lua
index dc37ec354..963e70686 100644
--- a/test/lua/module/pandoc-utils.lua
+++ b/test/lua/module/pandoc-utils.lua
@@ -39,20 +39,17 @@ return {
     end)
   },
 
-  group 'hierarchicalize' {
+  group 'make_sections' {
     test('sanity check', function ()
       local blks = {
         pandoc.Header(1, {pandoc.Str 'First'}),
         pandoc.Header(2, {pandoc.Str 'Second'}),
         pandoc.Header(2, {pandoc.Str 'Third'}),
       }
-      local hblks = utils.hierarchicalize(blks)
-      -- cannot create Elements directly; performing only an approximate
-      -- sanity checking instead of a full equality comparison.
-      assert.are_equal('Sec', hblks[1].t)
-      assert.are_equal('Sec', hblks[1].contents[1].t)
-      assert.are_equal(1, hblks[1].contents[2].numbering[1])
-      assert.are_equal(2, hblks[1].contents[2].numbering[2])
+      local hblks = utils.make_sections(true, 1, blks)
+      assert.are_equal('Div', hblks[1].t)
+      assert.are_equal('Header', hblks[1].content[1].t)
+      assert.are_equal('1', hblks[1].content[1].attributes['number'])
     end)
   },
 
diff --git a/test/writer.html4 b/test/writer.html4
index 6882d6b6c..fdfb56f15 100644
--- a/test/writer.html4
+++ b/test/writer.html4
@@ -442,7 +442,6 @@ Blah
 <li>Escaped <code>$</code>: $73 <em>this should be emphasized</em> 23$.</li>
 </ul>
 <p>Here’s a LaTeX table:</p>
-
 <hr />
 <h1 id="special-characters">Special Characters</h1>
 <p>Here is some unicode:</p>
diff --git a/test/writer.html5 b/test/writer.html5
index 9b0f19b64..35772350c 100644
--- a/test/writer.html5
+++ b/test/writer.html5
@@ -445,7 +445,6 @@ Blah
 <li>Escaped <code>$</code>: $73 <em>this should be emphasized</em> 23$.</li>
 </ul>
 <p>Here’s a LaTeX table:</p>
-
 <hr />
 <h1 id="special-characters">Special Characters</h1>
 <p>Here is some unicode:</p>