examine signature changed to include distance

- distance is INFINITE, 0, or a positive integer based on get_dist() between
the examiner and examinee's turfs when they are on the same Z. When the
examiner is dead or a ghost, distance is always 0.
- also updates /examine( implementations to use it!
- adds w_class_to_name proc for reusing "It is a X item." examine behavior.

code/modules/mining/ore_box.dm

@@ -13,9 +13,9 @@
 	var/stored_ore
 
 
-/obj/structure/ore_box/examine(mob/user)
+/obj/structure/ore_box/examine(mob/user, distance, infix, suffix)
 	. = ..()
-	if (!Adjacent(user) && !isobserver(user))
+	if (distance > 2 && !isobserver(user))
 		return
 	if (isliving(user))
 		add_fingerprint(user)