Previously the HTML writer was exceptional in not being
sensitive to the `--wrap` option. With this change `--wrap`
now works for HTML. The default (as with other formats) is
automatic wrapping to 72 columns.
A new internal module, T.P.Writers.Blaze, exports `layoutMarkup`.
This converts a blaze Html structure into a doclayout Doc Text.
In addition, we now add a line break between an `img` tag
and the associated `figcaption`.
Note: Output is never wrapped in `writeHtmlStringForEPUB`.
This accords with previous behavior since previously the HTML
writer was insensitive to `--wrap` settings. There's no real
need to wrap HTML inside a zipped container.
Note that the contents of script, textarea, and pre tags are
always laid out with the `flush` combinator, so that unwanted
spaces won't be introduced if these occur in an indented context
in a template.
Closes#7764.
Previously we stripped attribute prefixes, reading
`xml:lang` as `lang` for example. This resulted in
two duplicate `lang` attributes when `xml:lang` and
`lang` were both used. This commit causes the prefixes
to be retained, and also avoids invald duplicate
attributes.
Closes#6938.
