Classes
 ClassDescription
 Air AirJewel.as class.
 Earth Earth.as class.
 Fire Fire.as class.
 Jewel Jewel.as class.For as3 sprite based component. Add it to starling overlay stage(flash.display.Sprite).
 Jewel__ Jewel__.as class.For starling sprite based component. Define the parent holder(flash.display.Sprite) firstly,then add it to starling stage(starling.display.Sprite).
 Water Water.as class.