Merge pull request #611 from est77/master

Fixed stdosl.h OSL header.
Prefix macros that appear in the API with APPLESEED
Undo changes in CMakeLists files.
Merge pull request #612 from est77/est_macros_rename

Prefix macros that appear in the public API with APPLESEED to avoid possible clashes.
Added Phong closure, microfacet closure backwards compat improvements.