Endgame tweaks.

Now instead calls the proper round-end proc when finishing the round, allowing admins to interrupt restart if desired.
None of the current end game variants currently use over/underlays, they are now content with coloring space.
On endgame start, the entire world is now updated in a spawn() instead, reducing crippling lag.
Adds support to designate APCs are critical, these are not drained during world end events.
Fixes a couple of potential runtime errors if no escape points have bee mapped in.
People in wheelchairs and mechas can now enter the world end rift.
Cult walls no longer cultify over and over, indefinitely.

code/modules/mob/living/simple_animal/hostile/hostile.dm

@@ -214,8 +214,8 @@
 /mob/living/simple_animal/hostile/proc/check_horde()
 	if(emergency_shuttle.shuttle.location)
 		if(!enroute && !target_mob)	//The shuttle docked, all monsters rush for the escape hallway
-			if(!shuttletarget || (get_dist(src, shuttletarget) >= 2))
-				shuttletarget = pick(escape_list)
+			if(!shuttletarget && escape_list.len) //Make sure we didn't already assign it a target, and that there are targets to pick
+				shuttletarget = pick(escape_list) //Pick a shuttle target
 			enroute = 1
 			stop_automated_movement = 1
 			spawn()