More /vg/lighting tweaks

Rather then remove the light from all tiles, then re-add the light to all tiles, we just go thru each tile and diff the light level from the last value we added to it. (since this is tracked)
This cut the proc calls for updating lights in half.

Lighting objects now default to full brite rather then full dark so shuttles aren't as immersion breaking when they transit.

Made lighting more agressive about clearing empty lists.

code/controllers/subsystem/lighting.dm

@@ -36,18 +36,10 @@ SUBSYSTEM_DEF(lighting)
 	for (i in 1 to GLOB.lighting_update_lights.len)
 		var/datum/light_source/L = GLOB.lighting_update_lights[i]
 
-		if (L.check() || QDELETED(L) || L.force_update)
-			L.remove_lum()
-			if (!QDELETED(L))
-				L.apply_lum()
+		L.update_corners()
 
-		else if (L.vis_update) //We smartly update only tiles that became (in) visible to use.
-			L.smart_vis_update()
+		L.needs_update = LIGHTING_NO_UPDATE
 
-		L.vis_update   = FALSE
-		L.force_update = FALSE
-		L.needs_update = FALSE
-		
 		if(init_tick_checks)
 			CHECK_TICK
 		else if (MC_TICK_CHECK)