Use the separating axis theorem for tighter trace OBB culling

[dnk777]

Currently a check between a shape bounding sphere and a trace line (cylinder) is used. A prism that encloses two boxes (defined by trace extents and put at trace start/end) can be used as a tighter trace shape (rather than a cylinder). 4 or 6 planes of the prism can be chosen. Considering the fact some sides are pairwise parallel 2 or 3 dot products are to be computed for SAT tests. This approach fits use of SIMD instructions very nice given the fact we can compute/test 4 dot products in few instructions having a proper component layout.

[dnk777]

To be less vague not bounding spheres but bounding boxes of brushes and facets should be tested against these planes (as they're tighter than spheres). This requires testing 8 vertices against a plane in a general case but given plane normal signs a mask for selection of a nearest vertex from box bounds can be used (that is SIMD friendly as well).