restructure changelog file appending
- make appending code proper part of changelog with delayupdate/finalize
- use simplified appender that tracks pending data in memory
- eliminate old appendfile and helper classes
- update addchangegroup to use new interface and reuse the existing changelog
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.