Shuttle refactor (#2171)

Rewrites the area movement code used by shuttles & elevators in an effort to make it faster, more extensible, and generally easier to read. Also fixes some bugs relating to lighting & moving areas, such as lighting overlays suddenly being teleported into space for absolutely no reason.

Fixes #2161.
Fixes #2166.

code/modules/lighting/lighting_overlay.dm

@@ -30,7 +30,10 @@
 
 	update_overlay()
 
-/atom/movable/lighting_overlay/Destroy()
+/atom/movable/lighting_overlay/Destroy(force = FALSE)
+	if (!force)
+		return QDEL_HINT_LETMELIVE	// STOP DELETING ME
+
 	L_PROF(loc, "overlay_destroy")
 	SSlighting.lighting_overlays -= src
 	SSlighting.overlay_queue     -= src
@@ -54,13 +57,7 @@
 		else
 			warning("A lighting overlay realised it was in nullspace in update_overlay() and got deleted!")
 
-		qdel(src)
-		return
-
-	if (istype(T, /turf/space))
-		// I mean, this happens often and doesn't do any harm. Might as well silence the warning.
-		//warning("A lighting overlay realised it was attached to a space tile and got pooled!")
-		qdel(src)
+		qdel(src, TRUE)
 		return
 
 	// To the future coder who sees this and thinks
@@ -154,3 +151,6 @@
 	color = LIGHTING_BASE_MATRIX
 
 	return ..("color")
+
+/atom/movable/lighting_overlay/shuttle_move(turf/loc)
+	return

code/modules/lighting/lighting_turf.dm

@@ -23,7 +23,12 @@
 
 /turf/proc/lighting_clear_overlay()
 	if (lighting_overlay)
-		qdel(lighting_overlay)
+		if (lighting_overlay.loc != src)
+			var/turf/badT = lighting_overlay.loc
+			crash_with("Lighting overlay variable on turf [DEBUG_REF(src)] is insane, lighting overlay actually located on [DEBUG_REF(lighting_overlay.loc)] at ([badT.x],[badT.y],[badT.z])!")
+
+		qdel(lighting_overlay, TRUE)
+		lighting_overlay = null
 
 	L_PROF(src, "turf_clear_overlay")
 
@@ -170,9 +175,14 @@
 
 	recalc_atom_opacity()
 	lighting_overlay = old_lighting_overlay
+	if (lighting_overlay && lighting_overlay.loc != src)
+		// This is a hack, but I can't figure out why the fuck they're not on the correct turf in the first place.
+		lighting_overlay.forceMove(src, harderforce = TRUE)
+		
 	affecting_lights = old_affecting_lights
 	corners = old_corners
-	if ((old_opacity != opacity) || (dynamic_lighting != old_dynamic_lighting))
+
+	if ((old_opacity != opacity) || (dynamic_lighting != old_dynamic_lighting) || force_lighting_update)
 		reconsider_lights()
 
 	if (dynamic_lighting != old_dynamic_lighting)

code/modules/lighting/lighting_verbs.dm

@@ -42,7 +42,7 @@ var/list/admin_verbs_lighting = list(
 	SSlighting.corner_queue = list()
 	SSlighting.overlay_queue = list()
 
-/client/proc/lighting_reconsider_target(turf/T in world)
+/client/proc/lighting_reconsider_target(turf/T in turfs)
 	set category = "Lighting"
 	set name = "Reconsider Visibility"
 	set desc = "Triggers a visibility update for a turf."
@@ -57,7 +57,7 @@ var/list/admin_verbs_lighting = list(
 
 	T.reconsider_lights()
 
-/client/proc/lighting_build_overlay(turf/T in world)
+/client/proc/lighting_build_overlay(turf/T in turfs)
 	set category = "Lighting"
 	set name = "Build Overlay"
 	set desc = "Builds a lighting overlay for a turf if it does not have one."
@@ -72,7 +72,7 @@ var/list/admin_verbs_lighting = list(
 
 	T.lighting_build_overlay()
 
-/client/proc/lighting_clear_overlay(turf/T in world)
+/client/proc/lighting_clear_overlay(turf/T in turfs)
 	set category = "Lighting"
 	set name = "Clear Overlay"
 	set desc = "Clears a lighting overlay for a turf if it has one."