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/virus2/items_devices.dm

@@ -68,7 +68,7 @@
 					infect_virus2(target, src.virus2)
 		qdel(src)
 
-/obj/item/virusdish/examine(mob/user)
+/obj/item/virusdish/examine(mob/user, distance, infix, suffix)
 	. = ..()
 	if(basic_info)
 		. += "[basic_info] : <a href='?src=\ref[src];info=1'>More Information</a>"