adds slippery ice tiles (#4935)

code/game/turfs/flooring/flooring.dm

@@ -80,6 +80,11 @@ var/list/flooring_types
 	icon_base = "snowyplating"
 	flags = null
 
+/decl/flooring/snow/ice
+	name = "ice"
+	desc = "Looks slippery."
+	icon_base = "ice"
+
 /decl/flooring/snow/plating/drift
 	icon_base = "snowyplayingdrift"
 

code/game/turfs/simulated/outdoors/snow.dm

@@ -40,4 +40,17 @@
 		var/obj/S = new /obj/item/stack/material/snow(user.loc)
 		user.put_in_hands(S)
 		visible_message("[user] scoops up a pile of snow.", "You scoop up a pile of snow.")
-	return
+	return
+
+/turf/simulated/floor/outdoors/ice
+	name = "ice"
+	icon_state = "ice"
+	desc = "Looks slippery."
+
+/turf/simulated/floor/outdoors/ice/Entered(var/mob/living/M)
+	sleep(1 * world.tick_lag)
+	if(istype(M, /mob/living))
+		if(M.stunned == 0)
+			to_chat(M, "<span class='warning'>You slide across the ice!</span>")
+		M.SetStunned(2)
+		step(M,M.dir)

code/modules/mob/mob.dm

@@ -768,16 +768,19 @@
 	if(status_flags & CANSTUN)
 		facing_dir = null
 		stunned = max(max(stunned,amount),0) //can't go below 0, getting a low amount of stun doesn't lower your current stun
+		update_canmove()	//updates lying, canmove and icons
 	return
 
 /mob/proc/SetStunned(amount) //if you REALLY need to set stun to a set amount without the whole "can't go below current stunned"
 	if(status_flags & CANSTUN)
 		stunned = max(amount,0)
+		update_canmove()	//updates lying, canmove and icons
 	return
 
 /mob/proc/AdjustStunned(amount)
 	if(status_flags & CANSTUN)
 		stunned = max(stunned + amount,0)
+		update_canmove()	//updates lying, canmove and icons
 	return
 
 /mob/proc/Weaken(amount)
@@ -790,7 +793,7 @@
 /mob/proc/SetWeakened(amount)
 	if(status_flags & CANWEAKEN)
 		weakened = max(amount,0)
-		update_canmove()	//updates lying, canmove and icons
+		update_canmove()	//can you guess what this does yet?
 	return
 
 /mob/proc/AdjustWeakened(amount)