Blender Git Loki

NLA Bugfixes:

* Fixed crash when anim-playback is running and a strip beside a transition gets transformed.
Transition strips no-longer assume that their neighbours are action-clips, using the standard NLA-strip evaluation function instead to evaluate their neighbours. However, a check for ping-pong recursion needed to be added there, so that a transition beside a meta-strip, with the meta having a transition nested at the start of one of its levels, wouldn't fail with stack overflow.

* Moved 'Tweak Mode' menu entry to Edit menu, since it's not really that modal.