Blender Git Loki

IK work-in-progress commit;

- Removed old convention that only allowed one "IK" connection for Bones
in a joint. Was highly frustrating for editing trees or branches.
In a next commit, there will be a different method to define IK target
and IK root, so this option actually will become "Connect Bone" or so.

- the IK group name is gone, now is just an option "Tree IK". When IK
chains share a root they'll form a tree.
Todo is preventing conflicts here (will be for editor to define IK Root)

- Adding new IK constraint with CTRL+I activates Constraint