Prevents tick_check'ed sleeps/spawns from shutting out the MC

I don't know why I didn't do this before....

code/controllers/master.dm

@@ -232,6 +232,7 @@ var/CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 	while (1)
 		tickdrift = max(0, MC_AVERAGE_FAST(tickdrift, (((world.timeofday - init_timeofday) - (world.time - init_time)) / world.tick_lag)))
 		if (processing <= 0)
+			CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 			sleep(10)
 			continue
 
@@ -239,6 +240,7 @@ var/CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 		//	because sleeps are processed in the order received, so longer sleeps are more likely to run first
 		if (world.tick_usage > TICK_LIMIT_MC)
 			sleep_delta += 2
+			CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING - (TICK_LIMIT_RUNNING * 0.5)
 			sleep(world.tick_lag * (processing + sleep_delta))
 			continue
 
@@ -267,6 +269,7 @@ var/CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 			if (!error_level)
 				iteration++
 			error_level++
+			CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 			sleep(10)
 			continue
 
@@ -278,6 +281,7 @@ var/CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 				if (!error_level)
 					iteration++
 				error_level++
+				CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 				sleep(10)
 				continue
 		error_level--
@@ -288,6 +292,7 @@ var/CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 		iteration++
 		last_run = world.time
 		src.sleep_delta = MC_AVERAGE_FAST(src.sleep_delta, sleep_delta)
+		CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING - (TICK_LIMIT_RUNNING * 0.25) //reserve the tail 1/4 of the next tick for the mc.
 		sleep(world.tick_lag * (processing + sleep_delta))
 
 
@@ -445,7 +450,6 @@ var/CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 				return
 			queue_node = queue_node.queue_next
 
-	CURRENT_TICKLIMIT = TICK_LIMIT_RUNNING
 	. = 1
 
 //resets the queue, and all subsystems, while filtering out the subsystem lists