Build igloos and snowmen (#4811)

* adds packed snow brick material

* makes snow walls spawnable for mapping

* adds snowmen

craft them with snow. duh.

* snow spider triggers arachnophobia

also changelog.

code/game/objects/structures/snowman.dm

@@ -0,0 +1,24 @@
+/obj/structure/snowman
+	name = "snowman"
+	icon = 'icons/obj/snowman.dmi'
+	icon_state = "snowman"
+	desc = "A happy little snowman smiles back at you!"
+	anchored = 1
+
+/obj/structure/snowman/attack_hand(mob/user as mob)
+	if(user.a_intent == I_HURT)
+		user << "<span class='notice'>In one hit, [src] easily crumples into a pile of snow. You monster.</span>"
+		var/turf/simulated/floor/F = get_turf(src)
+		if (istype(F))
+			new /obj/item/stack/material/snow(F)
+		qdel(src)
+
+/obj/structure/snowman/borg
+	name = "snowborg"
+	icon_state = "snowborg"
+	desc = "A snowy little robot. It even has a monitor for a head."
+
+/obj/structure/snowman/spider
+	name = "snow spider"
+	icon_state = "snowspider"
+	desc = "An impressively crafted snow spider. Not nearly as creepy as the real thing."