Updates the atom_pool, now datum_pool, to handle any datum object.

Makes the garbage collector similarly robust. Continues the whole Destroy/qdel porting.

code/modules/overmap/ships/engines/engine.dm

@@ -57,4 +57,4 @@ var/list/ship_engines = list()
 		if (E.z == zlevel)
 			E.engines -= src
 			break
-	del(src)
+	qdel(src)

code/modules/overmap/ships/engines/thermal.dm

@@ -57,7 +57,7 @@
 	..()
 	controller = new(src)
 
-/obj/machinery/atmospherics/unary/engine/Del()
+/obj/machinery/atmospherics/unary/engine/Destroy()
 	..()
 	controller.die()