This implements weight rendering with the draw manager, with all drawing
options (Shading, wire, face masking, vertex masking).
This is part of T51208
Reviewers: campbellbarton
Subscribers: dfelinto
Differential Revision: https://developer.blender.org/D2654
- Added New Batch cache routine to get the split mesh for each material. (optimization needed)
- Did some shader modifications to create default_frag and support a somwhat correct fresnel for lamps (to finish)