col is a float4,   LUMINANCE_VECTOR a float3. results seemed cleaner this end doing a dot of the rgb than padding the lum
explicit downcasting for some halfs
prevents an infinite while loop by putting a cap of 4MS on occlusion queries.
Merge pull request #723 from Azaezel/lightRay_Cleanup

Light ray cleanup
Yikes. fatalityfix: need to create  a platformtimer for the reference.
Merge pull request #737 from Azaezel/queryStallPrevention

Query Stall Prevention