Previously we used our own homespun formatting. But this
produces over-long lines that aren't ideal for diffs in tests.
Easier to use something off-the-shelf and standard.
Closes#7580.
Performance is slower by about a factor of 10, but this isn't
really a problem because native isn't suitable as a serialization
format. (For serialization you should use json, because the reader
is so much faster than native.)
The `<p>` element is used for wrapping in cases were the contents would
otherwise not be allowed in a certain context. Unnecessary wrapping is
avoided, especially around quotes (`<disp-quote>` elements).
Closes: #7227
New formats:
- `jats_archiving` for the "Archiving and Interchange Tag Set",
- `jats_publishing` for the "Journal Publishing Tag Set", and
- `jats_articleauthoring` for the "Article Authoring Tag Set."
The "jats" output format is now an alias for "jats_archiving".
Closes: #6014
