Defining Part 1 - Code cleanup toward defines (#19262)

* This is only the beginning

* Update stack.dm

code/game/objects/structures/crates_lockers/closets/cardboardbox.dm

@@ -71,7 +71,7 @@
 				M.show_message("<span class='notice'>\The [src] has been cut apart by [user] with \the [WC].</span>", 3, "You hear cutting.", 2)
 			qdel(src)
 			return
-		if(istype(W, /obj/item/pen))
+		if(is_pen(W))
 			var/decalselection = input("Please select a decal") as null|anything in list("Atmospherics", "Bartender", "Barber", "Blueshield", "Captain",
 			"Cargo", "Chief Engineer",	"Chaplain",	"Chef", "Chemist", "Assistant", "Clown", "CMO", "Coroner", "Detective", "Engineering", "Genetics", "HOP",
 			"HOS", "Hydroponics", "Internal Affairs Agent", "Janitor",	"Magistrate", "Medical", "Mime", "Mining", "NT Representative", "Paramedic",

code/game/objects/structures/crates_lockers/closets/fireaxe.dm

@@ -39,7 +39,7 @@
 				to_chat(user, "<span class = 'caution'> You disable the locking modules.</span>")
 				update_icon(UPDATE_ICON_STATE)
 			return
-		else if(istype(O, /obj/item))
+		else if(isitem(O))
 			user.changeNext_move(CLICK_CD_MELEE)
 			var/obj/item/W = O
 			if(smashed || localopened)