Update SSOverlays (ported from Baystation) (#19051)

Our SSOverlays system is outdated, and is likely the cause of many of
the issues seen in #18895. It has also been linked to a massive server
performance decrease.

This brings an updated system from Baystation, hopefully with speed
increases.

Should be testmerged, ideally with #18895.

---------

Co-authored-by: Cody Brittain <cbrittain10@live.com>

code/game/objects/effects/decals/Cleanable/humans.dm

@@ -106,11 +106,11 @@
 				if(!S.blood_DNA)
 					S.blood_DNA = list()
 					S.blood_overlay.color = basecolor
-					S.add_overlay(S.blood_overlay)
+					S.AddOverlays(S.blood_overlay)
 				if(S.blood_overlay && S.blood_overlay.color != basecolor)
-					S.cut_overlay(S.blood_overlay, TRUE)
+					S.CutOverlays(S.blood_overlay, ATOM_ICON_CACHE_PROTECTED)
 					S.blood_overlay.color = basecolor
-					S.add_overlay(S.blood_overlay, TRUE)
+					S.AddOverlays(S.blood_overlay, ATOM_ICON_CACHE_PROTECTED)
 				if(blood_DNA)
 					S.blood_DNA |= blood_DNA.Copy()
 
@@ -217,8 +217,8 @@
 	blood.Blend(basecolor,ICON_MULTIPLY)
 
 	icon = blood
-	cut_overlays()
-	add_overlay(giblets)
+	ClearOverlays()
+	AddOverlays(giblets)
 
 /obj/effect/decal/cleanable/blood/gibs/up
 	random_icon_states = list("gib1", "gib2", "gib3", "gib4", "gib5", "gibup1","gibup1","gibup1")

code/game/objects/effects/decals/Cleanable/tracks.dm

@@ -127,7 +127,7 @@
 		update_icon()
 
 /obj/effect/decal/cleanable/blood/tracks/update_icon()
-	cut_overlays()
+	ClearOverlays()
 	color = "#FFFFFF"
 	var/truedir = 0
 
@@ -157,7 +157,7 @@
 		track.fresh = 0
 		track.overlay = I
 		stack[stack_idx] = track
-		add_overlay(I)
+		AddOverlays(I)
 
 /obj/effect/decal/cleanable/blood/tracks/footprints
 	name = "wet footprints"

code/game/objects/effects/decals/crayon.dm

@@ -28,6 +28,6 @@
 		shadeOverlay.Blend(shade,ICON_ADD)
 		SSicon_cache.crayon_cache["[type]_s"] = shadeOverlay
 
-	add_overlay(list(mainOverlay, shadeOverlay))
+	AddOverlays(list(mainOverlay, shadeOverlay))
 
 	add_hiddenprint(usr)

code/game/objects/effects/decals/warning_stripes.dm

@@ -7,5 +7,5 @@
 	var/turf/T = get_turf(src)
 	var/image/I = image(icon, icon_state = icon_state, dir = dir)
 	I.color = color
-	T.add_overlay(I, TRUE)	// Register it as priority so we don't lose it on icon update.
+	T.AddOverlays(I, ATOM_ICON_CACHE_PROTECTED)	// Register it as protected so we don't lose it on icon update.
 	qdel(src)

code/game/objects/effects/spiders.dm

@@ -62,7 +62,7 @@
 
 	if(prob(75))
 		var/image/web_overlay = image(icon, icon_state = "[initial(icon_state)]-overlay[pick(1, 2, 3)]", layer = ABOVE_HUMAN_LAYER)
-		add_overlay(web_overlay)
+		AddOverlays(web_overlay)
 
 /obj/effect/spider/stickyweb/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
 	if(air_group || height == 0)