Refine resetting faces

Living with the tweaks to overlays for a bit, I've come to the conclusion that there are two scenarios: either the context of the overlay is known or it isn't. The first scenario is like ace-window and avy. Here one needs to be careful, one can't ignore Emacs is text based. Setting font family, height, etc. can cause the surroundings to shift. The overlays need to blend in, at least somewhat. The second scenario is like magit-blame. Here the overlays stand on their own. This pull request introduces a second reset face in order to accommodate both scenarios. It also removes the reset face from one of the avy faces as I think without it the behavior is nicer. I'm terribly sorry for the inconvenience, especially since I stated in one of the patches leading up to this one, I wanted to spare you from having to play whack-a-mole. I think this is a robust solution.