PR Review guidelines

* We run on a 'use your judgement' system (for better or worse) and do

not have a strict nose-count rule. If you have a commit bit, then

you are trusted to use it and to know when to ask for more review.

* Do not self merge with the exception of un-breaking travis.

* Squashing is case-by-case. The balance is between burden on the

contributor, keeping a relatively clean history, and keeping a

history usable for bisecting. The only time we are really strict

about it is to eliminate binary files (ex multiple test image

re-generations) and to remove upstream merges.

* Be patient with new contributors.