* Rewrote the explosion sound to be more optimized and to be more dynamic.

Explosions that are close to you play the usual sound.
Explosions which are far away will play explosionfar.ogg but with volume differences depending on the distance.
Max cap bombs will play explosionfar.ogg for half of the station (140 tiles).
Explosion sounds will have panning, so stereo users will be able to tell the direction that the sound came from.
Small bombs will play much less than max cap bombs, and be quieter.
Changed playsound() to use less code. Playsound now loops through the player list, which means you do not have to check inside closets/objects/other mobs to play sounds.
Made all sounds use 3D sounds! This includes sounds which have less volume the further away you are from it.
The piano now uses 3D sounds.
Changed how the far explosion sound is calculated.
 Changed the heavy impact multiplier to 20.
Merge pull request #1801 from Giacom/explosion_sound

3D Sounds + Rewrote the explosion sound to be more optimized and to be more dynamic.