Qdel cleanup.

Replaces a few instances of del() with qdel().

code/modules/mining/abandonedcrates.dm

@@ -166,7 +166,7 @@
 			user << "<span class='danger'>The crate's anti-tamper system activates!</span>"
 			var/turf/T = get_turf(src.loc)
 			explosion(T, 0, 0, 1, 2)
-			del(src)
+			qdel(src)
 
 /obj/structure/closet/crate/secure/loot/proc/check_input(var/input)
 	if(length(input) != codelen)

code/modules/mob/living/silicon/ai/ai.dm

@@ -842,7 +842,7 @@ var/list/ai_verbs_default = list(
 // Cleaner proc for creating powersupply for an AI.
 /mob/living/silicon/ai/proc/create_powersupply()
 	if(psupply)
-		del(psupply)
+		qdel(psupply)
 	psupply = new/obj/machinery/ai_powersupply(src)
 
 #undef AI_CHECK_WIRELESS

code/modules/power/apc.dm

@@ -1170,7 +1170,7 @@ obj/machinery/power/apc/proc/autoset(var/val, var/on)
 
 	switch(severity)
 		if(1.0)
-			//set_broken() //now Del() do what we need
+			//set_broken() //now qdel() do what we need
 			if (cell)
 				cell.ex_act(1.0) // more lags woohoo
 			qdel(src)