Blender Git Loki

Gooseberry animation request: Paste flipped pose in action
and graph editor.

This was a tricky commit that was not so straightforward to make work.
The information for bones is not easy to come by in the animation curves,
however we do have some string manipulation tricks to make it happen.
For now committing to gooseberry branch for testing, it will be ported
to master after most usual use cases have been confirmed as working.

(Current test with all rotation modes and translation seems to work, but
Not sure how well this will hold up with drivers etc)