rename `stabilize` to `evolve` stabilize keep being valide but as Matt still like "Changeset Evolution" as a name evolve make more sense. Stabilize is a bit too tight to unstable too.

merge evolve and obsolete

sort import

Fix mercurial version check

Start a mercurial 2.2 branch This branch contains and old version compatible with mercurial 2.2. It's less complete and safe than later version.

update changelog

fix typo