Function overloads condensation (#18939)

Unified most of the procs into one definition, so there are no duplicate
around the codebase.
Marked some of the above as overridable if a good enough case can be
made for them (eg. external dependency or unlikely to be used).

code/modules/organs/organ_external.dm

@@ -961,15 +961,6 @@ Note that amputating the affected organ does in fact remove the infection from t
 	brute_ratio = brute_dam / (limb_loss_threshold * 2)
 	burn_ratio = burn_dam / (limb_loss_threshold * 2)
 
-// new damage icon system
-// adjusted to set damage_state to brute/burn code only (without r_name0 as before)
-/obj/item/organ/external/update_icon()
-	var/n_is = damage_state_text()
-	if (n_is != damage_state)
-		damage_state = n_is
-		return 1
-	return 0
-
 // new damage icon system
 // returns just the brute/burn damage code
 /obj/item/organ/external/proc/damage_state_text()

code/modules/organs/organ_icon.dm

@@ -48,10 +48,6 @@
 	if(eyes)
 		eyes.update_colour()
 
-/obj/item/organ/external/head/removed()
-	get_icon()
-	..()
-
 /obj/item/organ/external/head/get_icon()
 	..()
 	cut_overlays()

code/modules/organs/subtypes/machine.dm

@@ -417,10 +417,6 @@
 	vital = TRUE
 	emp_coeff = 0.1
 
-/obj/item/organ/internal/cell/Initialize()
-	robotize()
-	. = ..()
-
 /obj/item/organ/external/head/terminator
 	dislocated = -1
 	can_intake_reagents = 0

code/modules/organs/subtypes/standard.dm

@@ -240,6 +240,8 @@
 	return "[owner.get_pronoun("has")] [blood_type] running down [owner.get_pronoun("his")] neck!"
 
 /obj/item/organ/external/head/removed()
+	get_icon()
+
 	if(owner)
 		name = "[owner.real_name]'s head"
 		owner.drop_from_inventory(owner.glasses)
@@ -247,8 +249,8 @@
 		owner.drop_from_inventory(owner.l_ear)
 		owner.drop_from_inventory(owner.r_ear)
 		owner.drop_from_inventory(owner.wear_mask)
-		spawn(1)
-			owner.update_hair()
+		owner.update_hair()
+
 	..()
 
 /obj/item/organ/external/head/take_damage(brute, burn, damage_flags, used_weapon = null, list/forbidden_limbs = list(), var/silent)