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/assembly/assembly.dm

@@ -81,9 +81,9 @@
 /obj/item/assembly/process()
 	return PROCESS_KILL
 
-/obj/item/assembly/examine(mob/user)
+/obj/item/assembly/examine(mob/user, distance, infix, suffix)
 	. = ..()
-	if((in_range(src, user) || loc == user))
+	if(distance < 2)
 		if(secured)
 			. += "\The [src] is ready!"
 		else