Cache now has support for XML files stored in their own container. You can add them with `cache.addXML` (typically this is done from the Loader automatically for you) and get them with `cache.getXML(key)`. There is also `cache.checkXMLKey(key)`, `cache.checkKeys` and `cache.removeXML(key)`.
Instead of making a distinction between single frame images and Sprite
Sheets, I added a simple FrameData with one Frame to every image that
gets loaded. This way, a lot of the engine code can be simplified.
For instance, you can play animations on any Sprite without having to
check the “frame count” of its image anymore.
The engine doesn’t have to check for non-existing .frameData anymore.
An animation can keep on playing when an image happens to be set with 1
frame, continuing its animation when after that, another image is set
with multiple frames.
Think of it this way: an image with one frame is an animation of just
one frame.
Sprite.updateCrop is available if you wish to update an externally referenced crop rectangle.
Sprites and Images now have their own textures objects, they are no longer references to those stored in the global Pixi.TextureCache. This allows you to redefine the texture frame dynamically without messing up any other Sprites in your game, such as via cropping. They still share global Base Textures, so image references are kept to a minimum.
Sprite.resetFrame will revert the Sprites texture frame back to its defaults dimensions. This is called when you call Sprite.crop with no rectangle, to reset the crop effect, but can be userful in other situations so we've left it as a public method.
Cache.checkCanvasKey(key) - Check if a Canvas key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkTextureKey(key) - Check if a Texture key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkSoundKey(key) - Check if a Sound key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkTextKey(key) - Check if a Text key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkPhysicsKey(key) - Check if a Physics key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkTilemapKey(key) - Check if a Tilemap key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkBinaryKey(key) - Check if a Binary key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkBitmapDataKey(key) - Check if a BitmapData key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkBitmapFontKey(key) - Check if a BitmapFont key exists in the cache (thanks to @delta11 for the proposal)
Cache.checkJSONKey(key) - Check if a JSON key exists in the cache (thanks to @delta11 for the proposal)
