* Code cleanup
** Preview render code could be simplified, not used old preview.blend
** Remove unused functions from gpu_shader_material.glsl
** Customdata mask handling still assumes old draw types
** Move camera matrix code out of Render and into Freestyle, the only user
** Remove R_ORTHO, R_PANO, R_MBLUR flags
** Remove NODE_OLD_SHADING, NODE_NEW_SHADING
** Remove BLENDER_RENDER compat engine, find better system
* Remove or rename BI data
** Material colors still used by Cycles / Eevee
** AA enable, samples, full sample used by OpenGL render
** Maximum draw types on objects
** Hemi light type?
* Bigger tasks
** Add shader node support for OpenCollada material IO
** {T54696}
** {T54697}
** {T54656}
** Improve texture paint slot workflow (more slot types, better handling of no material, removing slots, ..)