Fixes for medals. (#5901)

# About the pull request

By design, you cannot wear uniform/armour with somebody else's medal.
Fine, but let it be checked upon trying to don the bemedalled object
yourself, not upon simply picking it up from the ground. It is
frustrating to constantly drop medals when trying to rearmour your
patients after revival/surgery.
(Ceterum censeo, letting doctors call themselves surgeons adds nothing
but an excuse to shirk pharmacy duties and to pretend to have priority
for deployment. But a bug is a bug.)

# Explain why it's good for the game

Is fixes.

# Changelog

:cl:
fix: Picking up clothes/armour with somebody else's medal attached no
longer makes the medal fall off (trying to wear them still does).
fix: Doctors calling themselves surgeons now properly get playtime
medals.
fix: Playtime medals now use assignments instead of backend paygrade
codes (e.g. "Awarded to Squad Leader John Doe" instead of "Awarded to
ME5 John Doe").
/:cl:

code/modules/clothing/under/ties.dm

@@ -154,18 +154,18 @@
 /obj/item/clothing/accessory/medal/on_attached(obj/item/clothing/S, mob/living/user, silent)
 	. = ..()
 	if(.)
-		RegisterSignal(S, COMSIG_ITEM_PICKUP, PROC_REF(remove_medal))
+		RegisterSignal(S, COMSIG_ITEM_EQUIPPED, PROC_REF(remove_medal))
 
-/obj/item/clothing/accessory/medal/proc/remove_medal(obj/item/clothing/C, mob/user)
+/obj/item/clothing/accessory/medal/proc/remove_medal(obj/item/clothing/C, mob/user, slot)
 	SIGNAL_HANDLER
-	if(user.real_name != recipient_name)
+	if(user.real_name != recipient_name && (slot == WEAR_BODY || slot == WEAR_JACKET))
 		C.remove_accessory(user, src)
 		user.drop_held_item(src)
 
 /obj/item/clothing/accessory/medal/on_removed(mob/living/user, obj/item/clothing/C)
 	. = ..()
 	if(.)
-		UnregisterSignal(C, COMSIG_ITEM_PICKUP)
+		UnregisterSignal(C, COMSIG_ITEM_EQUIPPED)
 
 /obj/item/clothing/accessory/medal/attack(mob/living/carbon/human/H, mob/living/carbon/human/user)
 	if(!(istype(H) && istype(user)))

code/modules/gear_presets/_select_equipment.dm

@@ -201,7 +201,7 @@
 				qdel(R)
 
 	if(flags & EQUIPMENT_PRESET_MARINE)
-		var/playtime = get_job_playtime(new_human.client, assignment)
+		var/playtime = get_job_playtime(new_human.client, rank)
 		var/medal_type
 
 		switch(playtime)
@@ -220,7 +220,7 @@
 		if(medal_type)
 			var/obj/item/clothing/accessory/medal/medal = new medal_type()
 			medal.recipient_name = new_human.real_name
-			medal.recipient_rank = current_rank
+			medal.recipient_rank = assignment
 
 			if(new_human.wear_suit && new_human.wear_suit.can_attach_accessory(medal))
 				new_human.wear_suit.attach_accessory(new_human, medal, TRUE)