Blender Git Loki

Fix T61796: Linking a collection with instances inside will place the instanced object in the scene.

Do not force to link indirectly linked collections into current scene,
that is usually not desired. Note that user can always add this link
manually if they want.

All this 'implicit instantiation' post-linking process is rather hairy
to get it correct, hope this time it's not breaking something else...