AnimationParser.spriteSheet() properly calculates sprite layout.

AnimationParser.spriteSheet() wasn't taking the margin or spacing parameters into account when calculating the numbers of sprites per row/column, nor was it allowing for extra power-of-two padding at the end.

AnimationManager.add() documentation said that 'frames' could be null, but the code couldn't handle this.

The documentation for StateManager.add() now correctly states that the default value for autoStart is false, not true.