This improves on the original fix to #5285 by preventing
other mixed lists (lists with a mix of Plain and Para
elements) that were allowed given the original fix.
HorizontalRule corresponds to <hr> element in the default output
format, HTML. Current HTML standard defines <hr> element as
"paragraph-level thematic break". In typography it is often
represented by extra space or centered asterism ("⁂"), but since
FB2 does not support text centering, empty line (similar to extra space)
is the only solution.
Line breaks, on the other hand, don't generate <empty-line />
anymore. Previously line breaks generated <empty-line /> element
inside paragraph, which is not allowed. So, this commit addresses
issue #2424 ("FB2 produced by pandoc doesn't validate").
FB2 does not have a way to represent line breaks inside paragraphs.
They are replaced with LF character, which is not rendered by
FB2 readers, but at least preserves some information.
Only <p> and <empty-line /> are allowed in titles,
but <p> has the same type as an ordinary paragraphs.
Therefore, there is no need to remove emphasis from titles.
Also, don't intersperse paragraph with empty lines.
<annotation> is not allowed inside <body> according to FictionBook2 XML schema. Besides that, the same information is already placed inside <description>.
Related bug: #2424
Previously bullet lists interacted in odd way with ordered lists.
For example, bullet lists nested in ordered list had incorrect
indentation. Besides that, indentation with spaces is not rendered
by FBReader and fbless. To avoid this problem, bullet lists are
indented by appending bullets to marker just the same way it is
done for ordered lists.
According to FB2 XML schema <empty-line /> cannot be placed inside
<p>. Linux FBReader can't display such paragraphs, e.g. any "loose"
lists produced by pandoc prior to this commit. Besides that,
FB2 writer placed <p> inside <p> when writing nested lists,
this commit fixes the bug.
Also this commit removes leading non-breaking space from ordered
lists for consistency with bullet lists.
Definition lists are not affected at all.
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.
