Documentation is now maintained in a separate source repository,
'tuxpaint-docs', which allows for easier and more consisten
translation of the documentation. Pulling in initial version of
these docs, which contain a variety of minor updates (and also a
few which had previously only been available as plain TXT are now
available as HTML).
Pulling in the English stuff.
* Add linked table of contents
* <cite> some terms
* <code> some paths
* Replace with CSS
* Brushes no longer limited to max 40x40 pixels in size
* Mac OS X is now macOS
* Other misc improvements
See "RELEASE.txt" for the invocation. Mended a few things prior
to final run of `tidy`, based on HTML Tidy's output.
Updated any affected TXT files via Makefile.
Documenting Mark Kim's recent changes:
* Less CPU-hungry progress bar (during Stamp loading)
* Verbose debugging options
* (Also, mentioned debugging _at all_, in INSTALL.txt)
Bumping version to 0.9.23a, to match the test build he's working
on for macOS.
