Blender Git Loki

Depsgraph: Fix missing updates when changing node tree topology

There were two issues here:

1. material_update did not do anything, because DEG_id_tag_update was storing
update tags in original IDs, which had nothing evaluated. Even more, material
update should have been called with evaluated version of material, Solved
this by copying update tag from original ID to a copied one.

However, perhaps DEG_id_tag_update should tag both original and copied ID,
so updates are never gets lots if some depsgraph is not visible.

2. Tagging material for update should ensure it's copied version of node tree is
up to date, otherwise material will still use old node tree.

This solves missing material updates when changing topology. Tweaking values is
still broken, because of GPUMaterial using pointer to original node's socket
value, which gets broken after copy-on-write of the node tree (pointers of nodes
are changing).