Rather than adding Euler angles, compose quaternions for gyros.
Removed remaining Orientation bits (and class itself), enforce limits on
head yaw/pitch/roll.
Reverse angles for mirror mode.
I got these backwards.
Have the Head control how orientations are added.
Revert to simply adding the Eulers.
Merge branch 'master' of https://github.com/worklist/hifi
Merged.
Merge pull request #470 from ey6es/master

Removed Orientation class, removed duplicate code in avatar-mixer.