Layers are now defines (#17949)

* Layers are now defines

* this looks better

* GAS_phil_LAYER

* no message

* remove the three unneeded defines

* no message

code/modules/vehicles/atv.dm

@@ -14,7 +14,7 @@
 	..()
 	if(!atvcover)
 		atvcover = image("icons/obj/vehicles.dmi", "atvcover")
-		atvcover.layer = MOB_LAYER + 0.1
+		atvcover.layer = ABOVE_MOB_LAYER
 
 
 obj/vehicle/atv/post_buckle_mob(mob/living/M)
@@ -26,7 +26,7 @@ obj/vehicle/atv/post_buckle_mob(mob/living/M)
 
 /obj/vehicle/atv/handle_vehicle_layer()
 	if(dir == SOUTH)
-		layer = MOB_LAYER+0.1
+		layer = ABOVE_MOB_LAYER
 	else
 		layer = OBJ_LAYER
 
@@ -51,13 +51,13 @@ obj/vehicle/atv/post_buckle_mob(mob/living/M)
 
 /obj/vehicle/atv/turret/handle_vehicle_layer()
 	if(dir == SOUTH)
-		layer = MOB_LAYER+0.1
+		layer = ABOVE_MOB_LAYER
 	else
 		layer = OBJ_LAYER
 
 	if(turret)
 		if(dir == NORTH)
-			turret.layer = MOB_LAYER+0.1
+			turret.layer = ABOVE_MOB_LAYER
 		else
 			turret.layer = OBJ_LAYER
 

code/modules/vehicles/scooter.dm

@@ -15,7 +15,7 @@
 
 /obj/vehicle/scooter/handle_vehicle_layer()
 	if(dir == SOUTH)
-		layer = MOB_LAYER+0.1
+		layer = ABOVE_MOB_LAYER
 	else
 		layer = OBJ_LAYER
 

code/modules/vehicles/speedbike.dm

@@ -2,7 +2,7 @@
 	name = "Speedbike"
 	icon = 'icons/obj/bike.dmi'
 	icon_state = "speedbike_blue"
-	layer = MOB_LAYER - 0.1
+	layer = LYING_MOB_LAYER
 	keytype = null
 	vehicle_move_delay = 0
 	var/overlay_state = "cover_blue"
@@ -11,13 +11,13 @@
 /obj/vehicle/space/speedbike/New()
 	..()
 	overlay = image("icons/obj/bike.dmi", overlay_state)
-	overlay.layer = MOB_LAYER + 0.1
+	overlay.layer = ABOVE_MOB_LAYER
 	overlays += overlay
 
 /obj/effect/overlay/temp/speedbike_trail
 	name = "speedbike trails"
 	icon_state = "ion_fade"
-	layer = MOB_LAYER - 0.2
+	layer = BELOW_MOB_LAYER
 	duration = 10
 	randomdir = 0
 

code/modules/vehicles/vehicle.dm

@@ -27,7 +27,7 @@
 //APPEARANCE
 /obj/vehicle/proc/handle_vehicle_layer()
 	if(dir != NORTH)
-		layer = MOB_LAYER+0.1
+		layer = ABOVE_MOB_LAYER
 	else
 		layer = OBJ_LAYER