This patch and the following intend to make the surface code more
manageable and are a preparation to add gl3 support. The code adds a
new IWineD3DBaseSurface surface type, which will contain the
non-rendering management code. IWineD3DSurface and IWineGDISurface
will be derived from IWineD3DBaseSurface, and IWineGL3Surface can be
added later.