BIG CHANGE: Platypus now uses the latest version of CreateJS: http://code.createjs.com/createjs-2013.09.25.min.js

1. This change requires that older SpriteSheet definitions be updated (use "speed" instead of "frequency")
2. "tick" events now pass the CreateJS tick event object, which uses "delta" instead of the original Platypus "deltaT" time increment.
3. Unrelated change: Mookie example sprite updated.