Evens out space lighting and prevents space fire/party alarms

Adds a dedicated lighting subarea for space turfs, and forces all space turfs to use it.  This evens out irregularities in lighting space turfs ("this empty space is slightly brighter than that empty space") and removes fire and party alarms from space tiles.

For now I have also made space lighting subareas unpowered.  I guess this operates on the theory that the tiles mysteriously teleport power between themselves (along with flashing red lights and party strobes) but it does not work on empty space.

code/controllers/_DynamicAreaLighting_TG.dm

@@ -223,16 +223,54 @@ turf/proc/shift_to_subarea()
 
 			A.tag = new_tag
 			A.lighting_subarea = 1
+			A.lighting_space = 0 // in case it was copied from a space subarea
 			A.SetLightLevel(light)
 
 			Area.related += A
 
 		A.contents += src	// move the turf into the area
 
+// Dedicated lighting sublevel for space turfs
+// helps us depower things in space, remove space fire alarms,
+// and evens out space lighting
+turf/space/shift_to_subarea()
+	lighting_changed = 0
+	var/area/Area = loc
+
+	var/find = findtextEx(Area.tag, "sd_L")
+	var/new_tag = copytext(Area.tag, 1, find)
+	new_tag += "sd_L_space"
+	if(Area.tag!=new_tag)	//skip if already in this area
+
+		var/area/A = locate(new_tag)	// find an appropriate area
+
+		if(!A)
+
+			A = new Area.type()    // create area if it wasn't found
+			// replicate vars
+			for(var/V in Area.vars)
+				switch(V)
+					if("contents","lighting_overlay","overlays")	continue
+					else
+						if(issaved(Area.vars[V])) A.vars[V] = Area.vars[V]
+
+			A.tag = new_tag
+			A.lighting_subarea = 1
+			A.lighting_space = 1
+			A.icon_state = null // in case the replicated area had an alert
+
+			//var/light = min(max(round(lighting_lumcount,1),0),lighting_controller.lighting_states)
+			A.SetLightLevel(4)
+
+			Area.related += A
+
+		A.contents += src	// move the turf into the area
+
 area
 	var/lighting_use_dynamic = 1	//Turn this flag off to prevent sd_DynamicAreaLighting from affecting this area
 	var/image/lighting_overlay		//tracks the darkness image of the area for easy removal
 	var/lighting_subarea = 0		//tracks whether we're a lighting sub-area
+	var/lighting_space = 0			// true for space-only lighting subareas
 
 	proc/SetLightLevel(light)
 		if(!src) return