CCSpriteBatchNode: Setting default content size to be layer bounds

* Setting default to CCSize.Zero is bad, because it breaks the transformation chain
CCLayer/CCScene: Remove manual setting of anchorPointInPoints

* this is not required
CCLabelBMFont: Fixing alignment issue

* When not setting a label dimensions, the width when laying out the label should be the content size
* Some general cleanup as well
* Incorporating SpriteBatchNode changes so that we don't have to perform our own PositionTransform updates