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`.

4 files changed, 2 insertions, 12 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>
 ```