[MIRROR] Replaced body zone magic strings with defines (#6004)

* Replaced body zone magic strings with defines

* merge conflicts

code/modules/mob/living/brain/brain_item.dm

@@ -5,7 +5,7 @@
 	throw_speed = 3
 	throw_range = 5
 	layer = ABOVE_MOB_LAYER
-	zone = "head"
+	zone = BODY_ZONE_HEAD
 	slot = ORGAN_SLOT_BRAIN
 	vital = TRUE
 	attack_verb = list("attacked", "slapped", "whacked")
@@ -112,7 +112,7 @@
 
 	add_fingerprint(user)
 
-	if(user.zone_selected != "head")
+	if(user.zone_selected != BODY_ZONE_HEAD)
 		return ..()
 
 	if((C.head && (C.head.flags_cover & HEADCOVERSEYES)) || (C.wear_mask && (C.wear_mask.flags_cover & MASKCOVERSEYES)) || (C.glasses && (C.glasses.flags_1 & GLASSESCOVERSEYES)))
@@ -122,7 +122,7 @@
 //since these people will be dead M != usr
 
 	if(!C.getorgan(/obj/item/organ/brain))
-		if(!C.get_bodypart("head") || !user.temporarilyRemoveItemFromInventory(src))
+		if(!C.get_bodypart(BODY_ZONE_HEAD) || !user.temporarilyRemoveItemFromInventory(src))
 			return
 		var/msg = "[C] has [src] inserted into [C.p_their()] head by [user]."
 		if(C == user)