Enigma Source (svn, archived)

- Splitted sound and sound_internal into:
SoundEngine, SoundEffectManager, MusicManager
- Stripped some blind functions, cleaned dependencies
Note:
- SoundEffectManager and MusicManager don't have any references
to SDL anymore - only exception is the datatype Uint32 which
is still used by MusicManager.
- All SDL_mixer-calls are now located in SoundEngine_SDL.
- SoundEffectManager and MusicManager are singletons in the
same sense as RatingManager. sound_engine still is an
auto_ptr, as it has to reference different classes
(SoundEngine_SDL or _null).