Merge pull request #1 from infinityb/master

It builds under Linux with this changeset
Add threading.
Fix broken supersampling jitter.

Was actually random sampling, which made it look awful.
Broken OBJ import.
Add limited OBJ support.

Currently limited to CookTorranceMaterials for imported OBJ meshes. No
rotation, scale, translation of imported Mesh objects.
Merge pull request #3 from gyng/obj_import

Limited OBJ import.
Faster Rng for Renderer