Fixes APC load totals periodically doubling

Also fixes areas updating excessively when update_use_power() was
called.

code/controllers/master_controller.dm

@@ -299,6 +299,7 @@ datum/controller/game_controller/proc/process_machines_power()
 		var/area/A = active_areas[i]
 		if(A.powerupdate && A.master == A)
 			A.powerupdate -= 1
+			A.clear_usage()
 			for(var/j = 1; j <= A.related.len; j++)
 				var/area/SubArea = A.related[j]
 				for(var/obj/machinery/M in SubArea)

code/game/machinery/machinery.dm

@@ -165,13 +165,9 @@ Class Procs:
 	use_power = new_use_power
 	
 	//force area power update
-	//use_power() forces an area power update on the next tick so have to pass the correct power amount for this tick
-	if (use_power >= 2)
-		use_power(active_power_usage)
-	else if (use_power == 1)
-		use_power(idle_power_usage) 
-	else
-		use_power(0)
+	var/area/A = get_area(src)
+	if(A && A.master)
+		A.master.powerupdate = 1
 
 /obj/machinery/proc/auto_use_power()
 	if(!powered(power_channel))

code/modules/power/apc.dm

@@ -1174,10 +1174,7 @@
 	lastused_light = area.usage(LIGHT)
 	lastused_equip = area.usage(EQUIP)
 	lastused_environ = area.usage(ENVIRON)
-	if(area.powerupdate)
-		if(debug) log_debug("power update in [area.name] / [name]")
-		area.clear_usage()
-
+	
 	lastused_total = lastused_light + lastused_equip + lastused_environ
 
 	//store states to update icon if any change
@@ -1195,6 +1192,9 @@
 
 	if(debug)
 		log_debug( "Status: [main_status] - Excess: [excess] - Last Equip: [lastused_equip] - Last Light: [lastused_light]")
+		
+		if(area.powerupdate)
+			log_debug("power update in [area.name] / [name]")
 
 	if(cell && !shorted)
 		//var/cell_charge = cell.charge