Port TG updating appearances (#17943)

* Get pants that match or else you gonna look silly yo

* Posters

* Fix other hud elements

* Rereviewed

* Update shotglass.dm

* Fix for new merged PRs

* Typo

* Coming across other stuff

* Update theblob.dm

* No takebacksies

* smh i forget to leave a comment

* Updated for the detgun and cards

* Should have rerun langserver again

* No longer plastic, more in scope

* Damn you bluespace

* Reverting turret logic, out of scope at this point

* Tweak that part

* Went over energy guns again, and fixed UI White's sprite sheet

* Welding masks, glasses, and JUSTICE

* Update portable_atmospherics.dm

* Cleaning up, clearing things up

* Review and suggestions

* Update valve.dm

* More tweaks

* Missing character

* Not distinct lightmasks, so they can be overlays

* Update generator.dm

* Add parameter so holodeck doesn't try to make a perfect copy

* Update unsorted.dm

* Spiders

* Better fix for spiders, fix vamps too

* Ghosts

* Update telekinesis.dm

* Cleaning up old procs

* It's set up to not copy datums... Unless they're in a list

* Donuts, duct tape, and detgun. D3VR coming to Early Access

* Update procs that interact with doors so they call update_state instead

* Forgot one spot, and actually might as well just force lock

* Cleaning up other things... Sigh, and kitty ears

* oops

* Getting used to how it works

* blinds

* Going back to the suit obscuring thing, so it doesn't update all the time

* Missed that from merging master

* I made this PR and forgot about it

* Fix runtimes in cards

* Make things a bit more unified

* Update update_icons.dm

* yarn, really?

* Update library_equipment.dm

* Update shieldgen.dm

* Every time Charlie merges something, I go back and see if I can improve things further

* what's this? more?

* Update misc_special.dm

* wow, paper

* Review

* More reviews

* To be sure, seems like being broken messed something sometimes

* Brought airlocks closer to how TG works to iron out some stuff

* Pizza and morgue

* Doesn't seem to hurt, tried with holodeck

* Revert "Doesn't seem to hurt, tried with holodeck"

This reverts commit 158529302b.

* Icon conflict

* Fix organ damage

* Don't ask how. Why. It's like that on prod too.

* Cutting down on things and updating from TG.

* More flexible. Just in case the thing you stuck it on didn't destroy.

* Hydro was one the things I touched earlier on, better rework it

* Reviews

* Cleaning up further, also bri'ish

* Undo a change I did, and switch over to a more recent implementation

* Update biogenerator.dm

* Rolling back to old airlocks, but with new duct taped note

* Functionally the same. I'd just rather not have the smoothing happen there

* Went over APCs again

* Fix welding helmet names in species files

* Update airlock.dm

* Update persistent_overlay.dm

* Oh, topic

code/game/objects/structures/displaycase.dm

@@ -28,7 +28,7 @@
 				trophy_message = showpiece_entry["trophy_message"]
 	if(start_showpiece_type)
 		showpiece = new start_showpiece_type (src)
-	update_icon()
+	update_icon(UPDATE_OVERLAYS)
 
 /obj/structure/displaycase/Destroy()
 	QDEL_NULL(electronics)
@@ -81,7 +81,7 @@
 		open = TRUE
 		new /obj/item/shard(drop_location())
 		playsound(src, "shatter", 70, TRUE)
-		update_icon()
+		update_icon(UPDATE_OVERLAYS)
 		trigger_alarm()
 
 /obj/structure/displaycase/proc/trigger_alarm()
@@ -95,17 +95,17 @@
 			playsound(src, 'sound/machines/burglar_alarm.ogg', 50, 0)
 			sleep(74) // 7.4 seconds long
 
-/obj/structure/displaycase/update_icon()
-	cut_overlays()
+/obj/structure/displaycase/update_overlays()
+	. = ..()
 	if(broken)
-		add_overlay("glassbox_broken")
+		. += "glassbox_broken"
 	if(showpiece)
 		var/mutable_appearance/showpiece_overlay = mutable_appearance(showpiece.icon, showpiece.icon_state)
 		showpiece_overlay.copy_overlays(showpiece)
 		showpiece_overlay.transform *= 0.6
-		add_overlay(showpiece_overlay)
+		. += showpiece_overlay
 	if(!open && !broken)
-		add_overlay("glassbox_closed")
+		. += "glassbox_closed"
 
 /obj/structure/displaycase/attackby(obj/item/I, mob/user, params)
 	if(I.GetID() && !broken && openable)
@@ -131,7 +131,7 @@
 			broken = FALSE
 			open = FALSE
 			obj_integrity = max_integrity
-			update_icon()
+			update_icon(UPDATE_OVERLAYS)
 	else
 		return ..()
 
@@ -174,7 +174,7 @@
 
 /obj/structure/displaycase/proc/toggle_lock()
 	open = !open
-	update_icon()
+	update_icon(UPDATE_OVERLAYS)
 
 /obj/structure/displaycase/attack_hand(mob/user)
 	user.changeNext_move(CLICK_CD_MELEE)
@@ -182,7 +182,7 @@
 		to_chat(user, "<span class='notice'>You deactivate the hover field built into the case.</span>")
 		dump()
 		add_fingerprint(user)
-		update_icon()
+		update_icon(UPDATE_OVERLAYS)
 		return
 	else
 	    //prevents remote "kicks" with TK