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/mob/dead/observer/observer.dm

@@ -169,7 +169,7 @@
 		set_cached_examine_icon(src, I, 200 SECONDS)
 	return I
 
-/mob/observer/dead/examine(mob/user)
+/mob/observer/dead/examine(mob/user, distance, infix, suffix)
 	. = ..()
 
 	if(is_admin(user))