* scripts/gitlog-to-changelog: New script. Taken from gnulib.
* scripts/git-log-fix: New file.
* scripts/git-log-footer: New file.
* scripts/git-hooks/commit-msg: New script.
* autogen.sh: Install commit-msg hook for git.
* 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.
