Projectiles bump fix, spawn() removal

Removes the spawn() in the Bump() proc of projectiles.
Fixes issue #1291
Cleaned up some files of projectiles/firing.dm
Instead of calling process(), when firing a projectile it will use fire()
Projectiles will now use qdel(), due to this, the emitters beams won't be in the object pool.
Changes the call from process() to fire() in all places where a projectile is created.
Mobs won't walk past projectiles anymore
Fixes issue #1332
Fix #5941