Merge pull request #505 from ArchieBeepBoop/zlevel

Ports Citadel Multi-Z Level fixes

code/modules/mob/living/living.dm

@@ -48,6 +48,15 @@
 	var/obj/item/clothing/head/mob_holder/holder = new(get_turf(src), src, (istext(can_be_held) ? can_be_held : ""), 'icons/mob/animals_held.dmi', 'icons/mob/animals_held_lh.dmi', 'icons/mob/animals_held_rh.dmi')
 	return holder
 
+/mob/living/onZImpact(turf/T, levels)
+	if(!isgroundlessturf(T))
+		ZImpactDamage(T, levels)
+	return ..()
+
+/mob/living/proc/ZImpactDamage(turf/T, levels)
+	visible_message("<span class='danger'>[src] crashes into [T] with a sickening noise!</span>")
+	adjustBruteLoss((levels * 5) ** 1.5)
+	Knockdown(levels * 50)
 
 /mob/living/proc/OpenCraftingMenu()
 	return

code/modules/mob/living/living_defines.dm

@@ -117,3 +117,5 @@
 	//List of active diseases
 	var/list/diseases = list() // list of all diseases in a mob
 	var/list/disease_resistances = list()
+
+	var/drag_slowdown = TRUE //Whether the mob is slowed down when dragging another prone mob

code/modules/mob/living/living_movement.dm

@@ -30,3 +30,14 @@
 		add_movespeed_modifier(MOVESPEED_ID_LIVING_TURF_SPEEDMOD, TRUE, 100, override = TRUE, multiplicative_slowdown = T.slowdown)
 	else
 		remove_movespeed_modifier(MOVESPEED_ID_LIVING_TURF_SPEEDMOD)
+
+/mob/living/proc/update_pull_movespeed()
+	if(pulling && isliving(pulling))
+		var/mob/living/L = pulling
+		if(drag_slowdown && L.lying && !L.buckled && grab_state < GRAB_AGGRESSIVE)
+			add_movespeed_modifier(MOVESPEED_ID_PRONE_DRAGGING, multiplicative_slowdown = PULL_PRONE_SLOWDOWN)
+			return
+	remove_movespeed_modifier(MOVESPEED_ID_PRONE_DRAGGING)
+
+/mob/living/canZMove(dir, turf/target)
+	return can_zTravel(target, dir) && (movement_type & FLYING)