Blender Git Loki

Disabled commit of three days ago to speedup and improve hairstrand
raytracing with a linedist (cylinder) check. It didn't behave OK on strands
set to be more than 1 pixel (not to mention 10 pixels), and I have no time
now to fully check and code it.

Which is not really important either... In general, all 3d papers talk about
using shadowbuffer shadows for hair, which gives much nicer results for
dense volumes of polygons.

This commit restores regular (flat polygon) raytrace shadow for strands.
Also fixes some nasty bugs as reported. :)