Blender Git Loki

2.5 - Constraints Editing + Keyframe Drawing Tweaks

Constraints:
* Adding constraints with targets should now work.
-- (When no target is provided, the code to create a new target is not yet in place again yet)
* Constraints can be added in Object and PoseModes again using the Ctrl-Shift-C hotkey.
* All constraints can now be cleared from the active Object or selected Bones using the Ctrl-Alt-C hotkey.
* Added warnings when adding constraints invalid for the current context, and removed the old add_constraint() function.
* Buttons window updates correctly after adding keyframes now

Keyframes Drawing:
* Removed un-necessary extra function-call for RB-Tree implementation, by inlining a special one-off case.
* Keyframe diamonds which are not within the viewable area are now not drawn (but filtering will still need to find them).