Previously we used the following Project Gutenberg conventions
for plain output:
- extra space before and after level 1 and 2 headings
- all-caps for strong emphasis `LIKE THIS`
- underscores surrounding regular emphasis `_like this_`
This commit makes `plain` output plainer. Strong and Emph
inlines are rendered without special formatting. Headings
are also rendered without special formatting, and with only
one blank line following.
To restore the former behavior, use `-t plain+gutenberg`.
API change: Add `Ext_gutenberg` constructor to `Extension`.
See #5741.
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.
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.
