devel: use the new 'config' argument of the develwarn in deprecwarn
Controling all deprecation warnings with the same config seems sensible. This
mirror a fix (about missing gating) submitted for stable but with the new API.
Mercurial's documentation is kept in reStructuredText format, which is
a simple plain text format that's easy to read and edit:
http://docutils.sourceforge.net/rst.html
It's also convertible to a variety of other formats including standard
UNIX man page format and HTML. You'll need to install Docutils:
http://docutils.sourceforge.net/
Use the Makefile in this directory to generate the man and HTML pages.