TG: Jetpacks can now use any gas.

The /obj/item/weapon/tank/jetpack path is now an empty jetpack, and oxygen and
carbon dioxide filled jetpacks are /obj/item/weapon/tank/jetpack/blue_jetpack
and /obj/item/weapon/tank/jetpack/black_jetpack respectively.

Added a new kind of disposal, the deathsposal (it's not called that in game).
It's the same as a normal disposal, except it has a red rim to indicate that it
leads to space.

code/modules/recycling/disposal.dm

@@ -421,7 +421,7 @@
 	proc/flush()
 
 		flushing = 1
-		flick("disposal-flush", src)
+		flick("[icon_state]-flush", src)
 
 		var/obj/structure/disposalholder/H = new()	// virtual holder object which actually
 											// travels through the pipes.