Now with more architecture changes!
CaelumEngine now stores an instance of IGame.
FileHelper.createStream() now contains a null check.
Created IPausable, delegated similar methods in other interfaces over to it.
Reverted the most recent IUpdatable change, because of the above change in CaelumEngine.
* Ditto with ThreadStoppable.rawUpdate().
Camera3D now uses setIsDirty().
Implmented ICamera.postRender().
Implemented IRenderEngine.getPriority().
Rearranged the methods in IRenderHUB.