Attack Proc fixes (#1259)

Baymerge changed the attack proc, i think by removing a default value, and a lot of things broke because they weren't using the function correctly.

This proc does three main things.

Adds a default to /obj/item/proc/attack to target the chest when no target zone is supplied.

Fixes the lack of a target zone in many attack procs, properly defining it so it'll get passed to the parent, and ensure that bodypart-specific targeting works.

Removes most instances of code to retrieve the user's selected zone, and instead to use the zone passed into the attack function. saves duplication of effort.

code/modules/customitems/item_defines.dm

@@ -328,7 +328,7 @@ All custom items with worn sprites must follow the contained sprite system: http
 
 	return
 
-/obj/item/weapon/implanter/fluff/attack(mob/M as mob, mob/user as mob)
+/obj/item/weapon/implanter/fluff/attack(mob/M as mob, mob/user as mob, var/target_zone)
 	if (!M.ckey || M.ckey != allowed_ckey)
 		return