Blender Git Loki

Merge branch 'master' into blender2.8

Notes:

- Changes in paint_vertex.c were simple to merge, mainly related on passing
evaluation context.

- Conflicts in EditDM and drawmesh.c are solved using code from blender2.8
branch. Those areas are deprecated and not to be used in final release.

However, it's possible that some reference code from master is lost, so
keep attention when adding alpha support for vertex painting.