Replaced DirectSound with BASSmod + Volume Slider

- Removed the very last components of DirectX7.
- Removed DirectSound and replaced it with BASSmod.
- Made some adjustments to Sub PopulateLists() to allow the new music
formats (mp3, ogg and wav)
- Added a volume slider option.
- Categorized the options in the *.ini file
- Added the DirectX8 *.dll in the executable's directory just to be
sure.