Non-planar Tilesort

Goal: support CAVE-like VR systems and curved display surfaces (via piece-wise linear approximation) with Tilesort. Also: don't require application modifications, if possible.
Problem: Tilesort SPU was written with the assumption that all mural tiles are co-planar. In particular, the bucketing algorithms assumed that.
Solution: per-server transformation matrices and a 3D view frustum bucketing mode.

Goal: support CAVE-like VR systems and curved display surfaces (via piece-wise linear approximation) with Tilesort. Also: don't require application modifications, if possible.