test-revert: move embedded script to its own file
Move the gen-revert-cases.py out of test-revert.t into its own file so
we can reuse it from other tests (specifically test-status-rev.t).
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.