add PhaserState.Generators.
renamed PhaserState.Microgame to PhaserMicrogame.
renamed PhaserState.createEventEmitter to SimpleEventEmitter.
added asset-loader.js, made export.js use it.
make PhaserState.Generators return js function defs.
get rid of PhaserState.preload, createSounds, createSprites.
exported HTML5 code is much cleaner now.