New branch in scala/scala repo: 2.12.0

[Seth Tisue]

A note on branching: there is now a separate 2.12.0 branch, in addition to the existing 2.12.x branch.

Most PRs should target 2.12.x, for eventual inclusion in Scala 2.12.1.

A PR should only target 2.12.0 if it's either critical, or zero risk (e.g. docs, spec).

Everything committed on the 2.12.0 branch will be merged forward onto 2.12.x as well.

GitHub, bless their hearts, now supports retargeting a PR after the fact:

https://github.com/blog/2224-change-the-base-branch-of-a-pull-request

so that'll make it easier to make sure everything ends up where it should be.

We don't have a 2.13 branch yet. Patience :-)

Seth Tisue / Scala team / Lightbend, Inc.