Merge pull request #615 from est77/master

Updated some OSL test scenes and all OSL ref images
Merge pull request #616 from est77/master

Added simple glass mono sppm scene (possible bug?)
Split shadow and transparency ray types
Simplify OSL shader execution code.
Added OSL opaque obj, transparent shadows test scene.
Merge pull request #617 from est77/est_transparency_raytype

Split shadow and transparency ray types.