Update to walk.js v1.12

Refactored code (walk.js < 25%, walkInterface.js < 14%)
Added walk.js to defaultScripts.js (suggestion)
New asymmetrical animation for flying and female standing animations
Updated setSkeletonOffset as per Interface / JS specification change (now specifying offsets in avatar frame, not global as before)
Smoothed out transitions
Implemented overlapping transitions (i.e. transitioning from a transition)
Frame by frame blending of flying animations (fwd, up, down)