NEWS updates

I've updated the NEWS file in master. Please all take a look and see
if you can think of something that's missing, or wrong.

The general guideline is that for the "New Functionality" section, we
should be pointing out the highlights that users may care about the
most (and that might make them upgrade :). For "Changed
Functionality", we'd ideally be documentating even smaller
incompatibilities; we won't be able to be comprehensive, but whatever
you can think of will be helpful.