Blender Git Loki

Outliner: Support multiple-objects drag'n'drop into collections

We now can drag multiple objects at once in the outliner. You we restricted to
working within a single outliner. Be sure to drag from the objects name, not
from its icon (otherwise it will try to parent it).

We don't use the same drag'n'drop system as IDs here. Which although I dislike
allowed for this solution to be local, and not dependent on the entire
drag'n'drop system of Blender.

This is a feature Andy Goralczyk has requested a long time ago.
Kudos for him for his request.