Revert "[MIRROR] Layer overhaul (#4503)" (#4509)

This reverts commit 8ac892d340.

code/game/objects/effects/countdown.dm

@@ -7,7 +7,7 @@
 
 	invisibility = INVISIBILITY_OBSERVER
 	anchored = TRUE
-	plane = GHOST_PLANE
+	layer = GHOST_LAYER
 	color = "#ff0000" // text color
 	var/text_size = 3 // larger values clip when the displayed text is larger than 2 digits.
 	var/started = FALSE

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

@@ -2,7 +2,7 @@
 	name = "pointer"
 	icon = 'icons/hud/screen_gen.dmi'
 	icon_state = "arrow"
-	plane = POINT_PLANE
+	layer = POINT_LAYER
 	duration = 25
 
 /obj/effect/temp_visual/point/Initialize(mapload, set_invis = 0)

code/game/objects/effects/misc.dm

@@ -45,6 +45,7 @@
 	icon = 'icons/effects/alphacolors.dmi'
 	icon_state = "white"
 	plane = LIGHTING_PLANE
+	layer = LIGHTING_LAYER
 	blend_mode = BLEND_ADD
 
 /obj/effect/abstract/marker

code/game/objects/effects/overlays.dm

@@ -64,12 +64,14 @@
 	invisibility = INVISIBILITY_ABSTRACT
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT
 
+	layer = ATMOS_GROUP_LAYER
 	plane = ATMOS_GROUP_PLANE
 
 /obj/effect/overlay/light_visible
 	name = ""
 	icon = 'icons/effects/light_overlays/light_32.dmi'
 	icon_state = "light"
+	layer = O_LIGHTING_VISUAL_LAYER
 	plane = O_LIGHTING_VISUAL_PLANE
 	appearance_flags = RESET_COLOR | RESET_ALPHA | RESET_TRANSFORM
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT
@@ -80,6 +82,7 @@
 	name = ""
 	icon = 'icons/effects/light_overlays/light_cone.dmi'
 	icon_state = "light"
+	layer = O_LIGHTING_VISUAL_LAYER
 	plane = O_LIGHTING_VISUAL_PLANE
 	appearance_flags = RESET_COLOR | RESET_ALPHA | RESET_TRANSFORM
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT

code/game/objects/effects/temporary_visuals/projectiles/tracer.dm

@@ -61,6 +61,7 @@
 
 /obj/effect/projectile/tracer/tracer/aiming
 	icon_state = "pixelbeam_greyscale"
+	layer = ABOVE_LIGHTING_LAYER
 	plane = ABOVE_LIGHTING_PLANE
 
 /obj/effect/projectile/tracer/wormhole

code/game/objects/structures/crates_lockers/closets.dm

@@ -88,7 +88,7 @@
 	if(broken || !secure)
 		return
 	//Overlay is similar enough for both that we can use the same mask for both
-	SSvis_overlays.add_vis_overlay(src, icon, "locked", 0, EMISSIVE_PLANE, dir, alpha)
+	SSvis_overlays.add_vis_overlay(src, icon, "locked", EMISSIVE_LAYER, EMISSIVE_PLANE, dir, alpha)
 	. += locked ? "locked" : "unlocked"
 
 /obj/structure/closet/examine(mob/user)