Merge pull request #6323 from Heroman3003/dirtining

Makes roundstart dirt work more properly

code/game/turfs/simulated.dm

@@ -13,6 +13,8 @@
 	var/to_be_destroyed = 0 //Used for fire, if a melting temperature was reached, it will be destroyed
 	var/max_fire_temperature_sustained = 0 //The max temperature of the fire which it was subjected to
 	var/can_dirty = TRUE	// If false, tile never gets dirty
+	var/can_start_dirty = TRUE	// If false, cannot start dirty roundstart
+	var/dirty_prob = 2	// Chance of being dirty roundstart
 	var/dirt = 0
 
 // This is not great.

code/game/turfs/simulated/floor.dm

@@ -41,9 +41,10 @@
 		set_flooring(get_flooring_data(floortype))
 	else
 		footstep_sounds = base_footstep_sounds
-	if(can_dirty)
-		if(prob(2))
-			new /obj/effect/decal/cleanable/dirt(src) //5% chance to start with dirt on a floor tile- give the janitor something to do
+	if(can_dirty && can_start_dirty)
+		if(prob(dirty_prob))
+			dirt += rand(50,100)
+			update_dirt() //5% chance to start with dirt on a floor tile- give the janitor something to do
 
 /turf/simulated/floor/proc/set_flooring(var/decl/flooring/newflooring)
 	make_plating(defer_icon_update = 1)