Matt Mackall <mpm@selenic.com> [Thu, 22 Mar 2007 23:37:44 -0500] rev 4261
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