This fixes numerous false positives coming out of the culling system.
AABB checks are now a full separating-axis check against the frustum, with the points of the frustum being compared to the planes of the box just as the points of the box were being compared to the planes of the frustum. This fixes large objects behind the camera not being culled correctly.
Some systems that used frustums that were (sometimes mistakenly?) unbounded on one or more side have been modified to be fully enclosed.
Also implemented decal atlas, so projectors and other stuff can be added.
Sidenote: Had to make RID hashable, so some unrelated includes changed
in order to include it in hashfuncs.h
