This includes a few fixes in the MBC_ api. The idea here is for this to be the only interface the render engines will deal with for the meshes. If we need to expose special options for sculpting engine we refactor this accordingly. But for now we are shaping this in a per-case base. Note: * We still need to hook up to the depsgraph to force clear/update of batch_cache when mesh changes (I'm waiting for Sergey Sharybin's depsgraph update for this though) * Also ideally we could/should use BMesh directly instead of DerivedMesh, but this will do for now. Note 2: In the end I renamed the `BKE_mesh_render` functions to `static mesh_render`. We can re-expose them as BKE_* later once we need it. Reviewers: merwin Subscribers: fclem Differential Revision: https://developer.blender.org/D2476