* scripts/gitlog-to-changelog: New script.  Taken from gnulib.
* scripts/git-log-fix: New file.
* scripts/git-log-footer: New file.
* doc/HACKING: Describe the ChangeLog policy
* ChangeLog: New file.
* Makefile.am (EXTRA_DIST): Add new files.
(gen-ChangeLog): New.
(dist-hook): Run gen-ChangeLog.

Rename all ChangeLog files to ChangeLog-2011.