mq: add --mq option to some commands
This causes them to operate on the queue repository as qcommit does, and
is nicer than hg -R $(hg root)
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://mercurial.selenic.com/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.