The changelog generation scripts used for releases are overly elaborate
and fragile. A Changelog is also no substitute for the Git log so now we
simply ship a static Changelog that points to the Git log instead.
This explicitly renames the cogl-2.0 reference manual to
cogl-2.0-experimental and renames the cogl-2.0 pkg-config file to
cogl-2.0-experimental.pc. Hopefully this should avoid
miss-understandings.
