When using 'protection flags' for XYZ rotations, inserting keys in
Poses resulted in wrong interpolations (doing -270 degrees instead of
+90 for example). This caused by converting quaternion to euler and
back...
Solved it by correcting the quaternion in the end for the rotation
sign of the original quaternion.
NOTE: Pose animators should be aware that inserting rotations keys of
180 degrees or larger will still make the key rotate along the shortest
path.
ddba16a752