Option to disable sound positioning

[Semphriss]

This allows users to disable sound positioning entirely from a config entry.

Observations, remarks, caveats:

• Sounds that are played far away from the screen are very audible when the option is activated. This may give players a hint about activity far away from the screen, as well as when certain things are disabled because they are too far away to be worth updating every frame.
• If the option is changed from the pause menu while in-game, the sounds that are already playing won't be updated.
• The 'sssssssssss' of the bomb is excessively loud. This may need a fix.