BF: Window wasn't beign garbage-collected due to circular reference with pyglet on_resize
ENH: improving interface for CRSLtd BitsSharp connection (not complete)
DOCS: restructuring to have more 'about' sections
Merge branch 'master' of github.com:psychopy/psychopy
Merge pull request #545 from jeremygray/master

RF: BaseVisual as base + mixins; closes #541