Rework of Multi Z vent crawling PR (#2775)

Reworks #2689
Includes: Vent crawling up and down.

Quote from original PR:

Main feature is that ventcrawling between Z levels now works perfectly. It takes 10 seconds to climb up or down a pipe...

code/modules/multiz/movement.dm

@@ -36,7 +36,7 @@
 		return eyeobj.zMove(direction)
 
 	// Check if we can actually travel a Z-level.
-	if (!can_ztravel())
+	if (!can_ztravel(direction))
 		to_chat(src, "<span class='warning'>You lack means of travel in that direction.</span>")
 		return FALSE
 
@@ -72,6 +72,14 @@
 	// Actually move.
 	Move(destination)
 	return TRUE
+	
+/mob/living/zMove(direction)
+	if (is_ventcrawling)
+		var/obj/machinery/atmospherics/pipe/zpipe/P = loc
+		if (istype(P) && P.can_z_crawl(src, direction))
+			return P.handle_z_crawl(src, direction)
+
+	return ..()
 
 /mob/eye/zMove(direction)
 	var/turf/destination = (direction == UP) ? GetAbove(src) : GetBelow(src)
@@ -102,13 +110,13 @@
  * @return	TRUE if the mob can move a Z-level of its own volition.
  *			FALSE otherwise.
  */
-/mob/proc/can_ztravel()
+/mob/proc/can_ztravel(var/direction)
 	return FALSE
 
-/mob/dead/observer/can_ztravel()
+/mob/dead/observer/can_ztravel(var/direction)
 	return TRUE
 
-/mob/living/carbon/human/can_ztravel()
+/mob/living/carbon/human/can_ztravel(var/direction)
 	if(incapacitated())
 		return FALSE
 
@@ -120,7 +128,7 @@
 			if(T.density)
 				return TRUE
 
-/mob/living/silicon/robot/can_ztravel()
+/mob/living/silicon/robot/can_ztravel(var/direction)
 	if(incapacitated() || is_dead())
 		return FALSE
 

code/modules/multiz/pipes.dm

@@ -19,7 +19,11 @@
 	var/maximum_pressure = 70*ONE_ATMOSPHERE
 	var/fatigue_pressure = 55*ONE_ATMOSPHERE
 	alert_pressure = 55*ONE_ATMOSPHERE
-
+	
+	var/travel_verbname = "UNDEFINED"
+	var/travel_direction_verb = "UNDEFINED"
+	var/travel_direction_name = "UNDEFINED"
+	var/travel_direction = "UNDEFINED"
 
 	level = 1
 
@@ -43,6 +47,11 @@
 		if(SOUTHWEST)
 			initialize_directions = SOUTH
 
+/obj/machinery/atmospherics/pipe/zpipe/Entered(mob/living/M)
+	if(istype(M))
+		M << span("notice", "You are in a vertical pipe section. Use [travel_verbname] from the IC menu to [travel_direction_verb] a level.")
+		. = ..()
+
 /obj/machinery/atmospherics/pipe/zpipe/hide(var/i)
 	if(istype(loc, /turf/simulated))
 		invisibility = i ? 101 : 0
@@ -118,6 +127,11 @@
 	name = "upwards pipe"
 	desc = "A pipe segment to connect upwards."
 
+	travel_verbname = "Move Upwards"
+	travel_direction_verb = "ascend"
+	travel_direction_name = "up"
+	travel_direction = UP
+
 /obj/machinery/atmospherics/pipe/zpipe/up/initialize()
 	normalize_dir()
 	var/node1_dir
@@ -156,6 +170,11 @@
 	name = "downwards pipe"
 	desc = "A pipe segment to connect downwards."
 
+	travel_verbname = "Move Downwards"
+	travel_direction_verb = "descend"
+	travel_direction_name = "down"
+	travel_direction = DOWN
+
 /obj/machinery/atmospherics/pipe/zpipe/down/initialize()
 	normalize_dir()
 	var/node1_dir

code/modules/ventcrawl/ventcrawl_atmospherics.dm

@@ -95,4 +95,24 @@ obj/machinery/atmospherics/trinary/isConnectable(var/obj/machinery/atmospherics/
 	return (target == node || ..())
 
 /obj/machinery/atmospherics/unary/isConnectable(var/obj/machinery/atmospherics/target)
-	return (target == node || ..())
+	return (target == node || ..())
+
+/obj/machinery/atmospherics/proc/can_z_crawl(var/mob/living/L, var/direction)
+	return FALSE
+
+/obj/machinery/atmospherics/pipe/zpipe/can_z_crawl(var/mob/living/L, var/direction)
+	if(L.is_ventcrawling && L.loc == src)
+		if(node2 && check_connect_types(node2,src))
+			if(direction == travel_direction)
+				return TRUE
+  
+/obj/machinery/atmospherics/proc/handle_z_crawl(var/mob/living/L, var/direction)
+	return
+
+/obj/machinery/atmospherics/pipe/zpipe/handle_z_crawl(var/mob/living/L, var/direction)
+	L << span("notice", "You start climbing [travel_direction_name] the pipe. This will take a while...")
+	playsound(loc, 'sound/machines/ventcrawl.ogg', 100, 1, 3)
+	if(!do_after(L, 100, needhand = 0, act_target = get_turf(src)) || !can_z_crawl(L, direction))
+		L << span("danger", "You gave up on climbing [travel_direction_name] the pipe.")
+		return FALSE
+	return ventcrawl_to(L, node2, null)