Better output formatting of forced line breaks

[timtylin]

This issues tracks the proposal to add a newline character \n after the associated LineBreak control character for certain writers, as per the discussion on pandoc-discuss.

The motivation for this is better output formatting of things written in markdown line-blocks, such as poetry, addresses, and algorithms. Since line-blocks do not have its own Block-level element, right now all lines from a line-block are simply concatenated with LineBreak. This change would make some outputs with large amount of line-block content much easier to inspect.

After looking through all the writers we have, the following writers stand out as candidates for this change:

• Dokuwiki
• HTML
• EPUB (via HTML)
• LaTeX
• MediaWiki
• OpenDocument
• Texinfo

[hftf]

I found what was breaking my program after installing it and Pandoc on a new computer. According to the 1.14 changelog:

Append newline to the LineBreak in Dokuwiki, HTML, EPUB, LaTeX, MediaWiki, OpenDocument, Texinfo writers (#1924, Tim Lin).

In 1.13:

$ echo "[Para [LineBreak]]" | pandoc -f native | tee foo
<p><br /></p>
$ xpath foo "p[not(text())]"
Found 1 nodes:
-- NODE --
<p><br /></p>

In 1.14:

$ echo "[Para [LineBreak]]" | pandoc -f native | tee foo
<p><br />
</p>
$ xpath foo "p[not(text())]"
No nodes found

I don't necessarily disagree with this change; I just found it very surprising.