[cmake-developers] New git workflow for conflicts in 'next'

[Brad King]

Hi Folks,

I've reconfigured the way our topic stage works to deal better
in cases that topics conflict when merging to next:

- Topics based on next will be rejected when they are pushed.

- Use of the topic stage is now *required*.  You will not be able
  to merge to 'next' yourself and push directly to the main repo.

- When a topic conflicts while merging to next the instructions
  printed are different than they were previously.  Basically it
  tells you how to merge the conflicting changes into your topic
  to resolve them before merging to next.

If you get a conflict and have trouble with the new instructions
please bring it up on this list.

-Brad