Add Sounds

-Looping wind sound plays in background
  -Currently starts at game launch, could be changed to start when play
is pressed
-Item pickup sounds (ammo, food, health, artifact)
-Footsteps
  -Not positional yet
  -Only works for crew who are ordered to move
    -Not sure where to hook in for other events
-Gun fire
  -Not positional yet
-Other sounds added, but not used yet