gas miners only update overlays when they actually need to

code/modules/atmospherics/machinery/other/miner.dm

@@ -29,6 +29,10 @@
 	idle_power_usage = 150
 	active_power_usage = 2000
 
+/obj/machinery/atmospherics/miner/Initialize()
+	. = ..()
+	set_active(active)				//Force overlay update.
+
 /obj/machinery/atmospherics/miner/examine(mob/user)
 	..()
 	if(broken)
@@ -40,31 +44,41 @@
 	var/turf/T = get_turf(src)
 	if(!isopenturf(T))
 		broken_message = "<span class='boldnotice'>VENT BLOCKED</span>"
-		broken = TRUE
+		set_broken(TRUE)
 		return FALSE
 	var/turf/open/OT = T
 	if(OT.planetary_atmos)
 		broken_message = "<span class='boldwarning'>DEVICE NOT ENCLOSED IN A PRESSURIZED ENVIRONMENT</span>"
-		broken = TRUE
+		set_broken(TRUE)
 		return FALSE
 	if(isspaceturf(T))
 		broken_message = "<span class='boldnotice'>AIR VENTING TO SPACE</span>"
-		broken = TRUE
+		set_broken(TRUE)
 		return FALSE
 	var/datum/gas_mixture/G = OT.return_air()
 	if(G.return_pressure() > (max_ext_kpa - ((spawn_mol*spawn_temp*R_IDEAL_GAS_EQUATION)/(CELL_VOLUME))))
 		broken_message = "<span class='boldwarning'>EXTERNAL PRESSURE OVER THRESHOLD</span>"
-		broken = TRUE
+		set_broken(TRUE)
 		return FALSE
 	if(G.total_moles() > max_ext_mol)
 		broken_message = "<span class='boldwarning'>EXTERNAL AIR CONCENTRATION OVER THRESHOLD</span>"
-		broken = TRUE
+		set_broken(TRUE)
 		return FALSE
 	if(broken)
-		broken = FALSE
+		set_broken(FALSE)
 		broken_message = ""
 	return TRUE
 
+/obj/machinery/atmospherics/miner/proc/set_active(setting)
+	if(active != setting)
+		active = setting
+		update_icon()
+
+/obj/machinery/atmospherics/miner/proc/set_broken(setting)
+	if(broken != setting)
+		broken = setting
+		update_icon()
+
 /obj/machinery/atmospherics/miner/proc/update_power()
 	if(!active)
 		active_power_usage = idle_power_usage
@@ -96,7 +110,7 @@
 	return FALSE
 
 /obj/machinery/atmospherics/miner/update_icon()
-	overlays.Cut()
+	cut_overlays()
 	if(broken)
 		add_overlay("broken")
 	else if(active)
@@ -106,7 +120,6 @@
 
 /obj/machinery/atmospherics/miner/process()
 	update_power()
-	update_icon()
 	check_operation()
 	if(active && !broken)
 		if(isnull(spawn_id))