New 2.0.x stable branch started

[Kai Grossjohann]

I started a 2.0.x stable branch at the 2.0.40 release.  Only bugfixes
will go into that branch.  The branch name is branch-2-0-stable, and
the starting point for that branch is called branchpoint-2-0-stable
(how boring).

The intention is to have 2.0.x be included in the next Emacs release,
whenever it will come out.

The trunk will now become 2.1.x and it will be a development series.
New features go here.

Now I just need to make sure that I never call the sync-with-Emacs
make target from the trunk working copy!

Kai