Ventcrawling fixes

d3athrow/vgstation13#4251
tgstation/-tg-station#9296

 - Fixes moving between pipeline datums not updating pipe vision
 - Fixes login() not updating pipe vision
 - Removes hardcoded limit of entering through unary machinery-- does
   nothing *now*
 - Can see pipes in darkness as fullbright
 - More sanity checks

code/ATMOSPHERICS/atmospherics.dm

@@ -25,12 +25,16 @@ Pipelines + Other Objects -> Pipe network
 	var/initialize_directions = 0
 	var/pipe_color
 
+	var/image/pipe_image
+
 	var/global/datum/pipe_icon_manager/icon_manager
 
 /obj/machinery/atmospherics/Destroy()
 	for(var/mob/living/M in src) //ventcrawling is serious business
 		M.remove_ventcrawl()
-		M.loc = src.loc
+		M.forceMove(src.loc)
+	if(pipe_image)
+		del(pipe_image) //we have to del it, or it might keep a ref somewhere else
 	..()
 
 // Find a connecting /obj/machinery/atmospherics in specified direction.
@@ -163,6 +167,9 @@ obj/machinery/atmospherics/proc/check_connect_types_construction(obj/machinery/a
 			user.forceMove(target_move.loc) //handles entering and so on
 			user.visible_message("You hear something squeezing through the ducts.", "You climb out the ventilation system.")
 		else if(target_move.can_crawl_through())
+			if(target_move.return_network(target_move) != return_network(src))
+				user.remove_ventcrawl()
+				user.add_ventcrawl(target_move)
 			user.loc = target_move
 			user.client.eye = target_move //if we don't do this, Byond only updates the eye every tick - required for smooth movement
 			if(world.time - user.last_played_vent > VENT_SOUND_DELAY)

code/ATMOSPHERICS/components/unary/unary_base.dm

@@ -66,7 +66,7 @@
 	return_network(obj/machinery/atmospherics/reference)
 		build_network()
 
-		if(reference==node)
+		if(reference == node || reference == src)
 			return network
 
 		return null
@@ -89,7 +89,7 @@
 		if(reference==node)
 			del(network)
 			node = null
-			
+
 		update_icon()
 		update_underlays()