Blender Git Loki

Remove mode handling

This commit reverts 21aefa098f4935597a759e199153e9b55279ff8a.
This commit reverts 2ab98cca19cb3acd3da61b5f71a61a1139f1713e.

Mode weights must not affect the BSDF's PDF

Add mode controls

This is useful only for separating each light mode (R, TT, TRT, TRRT+)
and see how the shader behaves in each.

Fix Filter Glossy handling

Previously, Filter Glossy was applied to the logistic distribution's
parameters. This wasn't noticeable unless one traced bsdf_blur.

Now, bsdf->v, s and m0_roughness are only used within the shader; the
corresponding (roughness) parameters are roughness, radial_roughness and
coat.