Changed the IFF loading function to only look for the FORM string
when The Vampire Diaries is running. This prevents a chunk read error
in at least one file in nancy2.
The resource manager now keeps track of its cif trees and calls to loadImage() and loadData() don't need to specify a cif tree. In order to support The Vampire Diaries, IFFs can now be loaded from their own dedicated .iff file, and the engine doesn't require a cif tree to be loaded on boot.
Made all states (Scene, Credits, Help, etc.) singletons, as well as subclasses of a common State parent with a proper state switching API. Moved the OnPause virtual function from RenderObject to ActionRecord and hooked it into the state switching code. Also got rid of the NancyEngine pointer that got passed around between most classes, and replaced it with several convenience macros. As a result of these changes action records that render to the viewport no longer disappear after opening the menu, and state changes feel snappier.
Rewrote most of the engine using a much more object-oriented approach and using more of ScummVM's common classes. This design deviates quite a lot from the original engine's, but should be more maintainable and extensible in the future.
