BitmapData.copyTransform allows you to draw a Game Object to the BitmapData, using its `worldTransform` property to control the location, scaling and rotation of the object. You can optionally provide
BitmapData.drawGroup now uses the new `copyTransform` method, to provide for far more accurate results. Previously nested Game Objects wouldn't render correctly, nor would Sprites added via `addChild` to another Sprite. BitmapText objects also rendered without rotation taken into account, and the Sprites smoothing property was ignored. All of these things are now covered by the new drawGroup method, which also handles full deep iteration down the display list.
The `DisplayObject.worldScale` value didn't multiply the local objects scale into the calculation, meaning the value wasn't a true representation of the objects world scale.
Group.onChildInputUp is a new Signal that you can listen to. It will be dispatched whenever any immediate child of the Group emits an `onInputUp` signal itself. This allows you to listen for a Signal from the Group, rather than every Sprite within it.
Group.onChildInputOver is a new Signal that you can listen to. It will be dispatched whenever any immediate child of the Group emits an `onInputOver` signal itself. This allows you to listen for a Signal from the Group, rather than every Sprite within it.
Group.onChildInputOut is a new Signal that you can listen to. It will be dispatched whenever any immediate child of the Group emits an `onInputOut` signal itself. This allows you to listen for a Signal from the Group, rather than every Sprite within it.
Group.addAt has been refactored to be a simple call to `Group.add`, removing lots of duplicate code in the process.
Group.create has a new optional argument `index` which controls the index within the group to insert the child to. Where 0 is the bottom of the Group. It also now makes proper use of `Group.add`, cutting down on more duplicate code.
Group.createMultiple now returns an Array containing references to all of the children that the method created.
The purpose of `processInteractiveObjects` is to work out which Game Object the Pointer is going to
interact with. It works by polling all of the valid game objects, and then slowly discounting those
that don't meet the criteria (i.e. they aren't under the Pointer, are disabled, invisible, etc).
Eventually a short-list of 'candidates' is created. These are all of the Game Objects which are valid
for input and overlap with the Pointer. If you need fine-grained control over which of the items is
selected then you can use this callback to do so.
The callback will be sent 3 parameters:
1) A reference to the Phaser.Pointer object that is processing the Items.
2) An array containing all potential interactive candidates. This is an array of `InputHandler` objects, not Sprites.
3) The current 'favorite' candidate, based on its priorityID and position in the display list.
Your callback MUST return one of the candidates sent to it.
