GitHub release model.

[Marcus Hirt]

Hi all,

It's time we start considering how we want to manage the source across
releases. One model that looks attractive is what is done in the JavaFX
project. We'll branch for major releases and tag commits in those branches
for our actual releases.

If this is not enough, and we ever feel the need to work on several minor
releases in parallel for a specific major release, we could create branches
as needed from the major release branches.

We could name the branches jmc7, jmc8 etc. And yep, we could fold in the
jmc7 repo being ported to GitHub into a jmc7 branch in the jmc repo and
retire the jmc7 repo.

What do you think?

Kind regards,
Marcus