Plays back a sound.

Required parameters:

- value = group_no, sound_no (int)
  group_no and sound_no correspond to the identifying pair that you assigned each sound in the player's snd file. To play back a sound from "fight.snd", precede group_no with an "F".

Optional parameters:

- volume = volume_level (int)
  volume_level is 0 for normal volume, positive for louder, and negative for softer.

Examples:

`; Plays back sound 2,0 from the player's SND file
type = PlaySnd
value = 2,0
; Plays back sound 5,2 from fight.snd
type = PlaySnd
value = F5,2`