* Started porting over to python, menus nearly done, header WIP.
* Game Properties panel is in python too
* Deprecated "Tiles" as a per face flag here, now it's always on
the image, used to be both, working in a very confusing way.
Unlikely someone actually had a purpose for this being per face.
* Remove GPC_PolygonMaterial.cpp/h, it's not actually used anymore,
so I don't want to bother updating it.
* Fix crash in image painting (own mistake in porting over bugfix
from 2.4x).
401b58cb45