This replaces the LPDIRECTSOUNDBUFFER pointer with a pure virtual class and an implementation that wraps the LPDIRECTSOUNDBUFFER, allowing other sound implementations without having to simulate the exact alignment of a DIRECTSOUNDBUFFER object.
Additionally, moves the DSInit and DSUninit calls out of the SoundCore.cpp file (into a new DXSoundBuffer.cpp (for Windows)), allowing them to be appropriately reimplemented in a non-DirectSound environment.
