Unified *_rcpath so the interface is similar across operating systems
Changed os_rcpath to combine system_rcpath and user_rcpath. Changed
system_rcpath and user_rcpath to both return a list of paths to add to the
combined rcpath for both Windows NT and other platforms.
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.