patchbomb: make `hg email` reusable for other patch sources
Adds two internal options, patches and patchnames, which allow other extensions
to email a given set of patches. The pbranch extension needs this to send its
patches which are diffs between topic branches.
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://www.selenic.com/mercurial/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.