Human icon key & preferences tweaks (#3274)

changes:

Reworked how human body icon keys are generated; resulting keys should be much shorter now and involve less duplication of the same string.
Players are now shown a message when they try to add markings to a species that has none available.
Admin revive for human-types will now also re-apply their organ and marking prefs.
Admin revive now also resets shock_stage (fixes rejuv'd mobs being slow for a while)

code/controllers/subsystems/icon_cache.dm

@@ -52,6 +52,8 @@
 	var/list/human_underwear_cache = list()
 	var/list/human_undershirt_cache = list()
 	var/list/human_socks_cache = list()
+	var/list/organ_keymap = list()
+	var/current_organ_keymap_idex = 1
 	// This is an assoc list of all icon states in `icons/mob/collar.dmi`, used by human update-icons.
 	var/list/collar_states
 	var/list/uniform_states
@@ -64,6 +66,16 @@
 	for (var/i in icon_states('icons/mob/collar.dmi'))
 		collar_states[i] = TRUE
 
+/datum/controller/subsystem/icon_cache/proc/get_organ_shortcode(obj/item/organ/external/organ)
+	if (QDELETED(organ))
+		return null
+
+	var/key = organ.get_mob_cache_key(FALSE)
+	. = organ_keymap[key]
+	if (!.)
+		organ_keymap[key] = "organ[current_organ_keymap_idex++]"
+		. = organ_keymap[key]
+
 /datum/controller/subsystem/icon_cache/proc/setup_uniform_mappings()
 	uniform_states = list()
 	for (var/i in icon_states('icons/mob/uniform.dmi'))