add Core#_createTouchToStartScene
display the string using Label in TouchToStartScene
add enchant.ENV.USE_TOUCH_TO_START_SCENE
change condition for display TouchToStartScene
play silent sound in TouchToStartScene if use webaudio
Fixed bug: Setting Sprite.frame to the same frame sequence would cause the animation to freeze, which was being caused by shallow comparison condition in frame.set() + Added functionality: Dispatch Event.ANIMATION_END when null element is encountered in Sprite frame sequence.
Merge branch 'touch-to-start' into develop

Conflicts:
	dev/src/Env.js
add jsdoc comment for enchant.ENV.USE_TOUCH_TO_START_SCENE
modify jsdoc comment for enchant.ENV.USE_TOUCH_TO_START_SCENE
modify Core#_createTouchToStartScene to simplify
Merge pull request #258 from bytehala/develop

Fixed bug: Animation freezes when setting equal frame
fix jshint errors on pull request #258
Merge branch 'develop'