Gamepad/joystick support added

I have now added support for PS4 gamepad.  Move using left stick or d-pad.  Throw bone using square, steak using cross, cookie using circle, sandwich using triangle.  Pause using R1.  Can also play the WebGL build on ios using the backbone controller - possibly other similar controllers will work but I haven't got them to try, please let me know if you do try them!