Added OSL dtime and dPdtime support. Get globals info from shader groups. Changes to optimize ShadingPoint -> ShadingGlobals conversions.
Use the new api to find the globals needed by a shader group.
Fix conflicts.
Small improvements.
Clean code.
Added hook for OSL surfacearea. Added sample OSL velocity scene.
Reverted HasOSLShaderGlobals name change.
Fixed PR coments, solved conflicts.
Merge pull request #557 from est77/OSL_time

OSL improvements / refactors + time related stuff