Merge pull request #613 from est77/master

Added Phong closure, microfacet closure backwards compat improvements.
OSL special version of Ashikmin Shirley BRDF.
OSL special version of Ashikmin Shirley BRDF.
Merge pull request #614 from est77/est_osl_ashikhmin

OSL special version of Ashikmin Shirley BRDF
fixed typos.
fixed typos.
Updated OSL scenes and ref images.
Updated OSL scenes and ref images.