Blender Git Loki

Merge branch 'master' into cycles_disney_brdf

Updated copyright for the new files.

Switched from multiplication of base and subsurface color to blending
between them using the subsurface parameter.

Fixed a bug that caused an additional white diffuse closure call when using
path tracing.

Merge branch 'master' into cycles_disney_brdf

Fixed the broken GLSL shader and implemented the Disney BRDF in the
real-time view port.

Fix to comply strict compiler flags and some code cleanup

Merge branch 'master' into cycles_disney_brdf

Renamed the Disney BSDF to Principled BSDF.

Removed reflection call when roughness is low because of artifacts.

Indication if to use fresnel is now handled via the type of the BSDF.

Fixed an error in the clearcoat where it appeared too bright for default
light sources (like directional lights)

Resolved inconsistencies in using tabs and spaces

Improved the clearcoat part by using GTR1 instead of GTR2

Use reflection BSDF for glossy reflections when roughness is 0.0 to
reduce computational expense and some code cleanup

Code cleanup includes:
- Code style cleanup and removed unused code
- Consolidated code in the bsdf_microfacet_multi_impl.h to reduce
some computational expense

Fixed glossy reflections and refractions for low roughness values and
cleaned up the code.

For low roughness values, the reflections had some strange behavior.

Removed default values in setup functions and added extra functions for
GGX with fresnel.

Switched from uniform to cosine hemisphere sampling for the diffuse and
the sheen part.

Removed the color parameters from the diffuse and sheen shader and use
them as closure weights instead.

Fixed the issue with artifacts when using anisotropy without linking the
tangent input to a tangent node.