Blender Git Loki

Keying Sets: Added 'remove selected from active set' (Alt-K) operator in Outliner

* Cleaned up the helper functions for the Outliner operators which deal with Keying Sets
* Fixed a few minor bugs in the Keying Sets API that won't show up with the current tools, but may crop up later
* Added a new method to find a 'matching' path in a Keying Set. Now adding a new path to a Keying Set will firstly check if there is any similar path already, and skip adding another path.