Pandoc's AST is translated into the Jira AST, which is then rendered by
the dedicated Jira printer.
The following improvements are included in this change:
- non-jira raw blocks are fully discarded instead of showing as blank
lines;
- table cells can contain multiple blocks;
- unnecessary blank lines are removed from the output;
- markup chars within words are properly surrounded by braces;
- preserving soft linebreaks via `--wrap=preserve` is supported.
Note that backslashes are rendered as HTML entities, as there appears no
alternative to produce a plain backslash if it is followed by markup.
This may cause problems when used with confluence, where rendering seems
to fail in this case.
Closes: #5926
Backslash-escaping is used instead of HTML entities, as escaped
characters are easier to read this way. Furthermore, Confluence, which
seems to use a subset of Jira markup, seems to get confused by HTML
entities.
