Blender Git Loki

Fix T40164: Linking a Group of linked Groups don't take Dupli Visibility
correctly.

Problem was that object layers are defined by duplis as the top-level
duplicator layers. This happens //during// the duplilist construction,
which breaks group layer checks for subsequent instances and hides them.
Now the duplilist generators leave Object DNA untouched, the
modification of layers for drawing, rendering, etc. happens afterward
in the duplilist_apply/restore functions, as a kind of second pass.