MouseTracker - Pointer over/out event fixes

Fixes #152, #404, #420, #427
Well I can't find the example of course :) So what's the proper way to do this? I'd much rather use the dot syntax over the key string syntax, which means I chose that way for a reason I wish I could remember. My only worry is cross-browser compatibility, and currently both ways work on the only two browsers that have touch-action implemented: IE 10/11 and Chrome (latest). Thanks!