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/shieldgen/directional_shield.dm

@@ -209,9 +209,9 @@
 		else
 			playsound(src, 'sound/machines/defib_safetyOff.ogg', 75, 0)
 
-/obj/item/shield_projector/examine(var/mob/user)
+/obj/item/shield_projector/examine(mob/user, distance, infix, suffix)
 	. = ..()
-	if(Adjacent(user))
+	if(distance < 2)
 		. += "Its shield matrix is at [round( (shield_health / max_shield_health) * 100, 0.01)]% strength."
 
 /obj/item/shield_projector/emp_act(var/severity)

code/modules/shieldgen/handheld_defuser.dm

@@ -47,7 +47,7 @@
 		STOP_PROCESSING(SSobj, src)
 	to_chat(usr, "You turn \the [src] [enabled ? "on" : "off"].")
 
-/obj/item/shield_diffuser/examine(mob/user)
+/obj/item/shield_diffuser/examine(mob/user, distance, infix, suffix)
 	. = ..()
 	. += "The charge meter reads [cell ? cell.percent() : 0]%"
-	. += "It is [enabled ? "enabled" : "disabled"]."
+	. += "It is [enabled ? "enabled" : "disabled"]."

code/modules/shieldgen/shield_diffuser.dm

@@ -67,8 +67,8 @@
 	alarm = round(max(alarm, duration))
 	update_icon()
 
-/obj/machinery/shield_diffuser/examine(var/mob/user)
+/obj/machinery/shield_diffuser/examine(mob/user, distance, infix, suffix)
 	. = ..()
 	. += "It is [enabled ? "enabled" : "disabled"]."
 	if(alarm)
-		. += "A red LED labeled \"Proximity Alarm\" is blinking on the control panel."
+		. += "A red LED labeled \"Proximity Alarm\" is blinking on the control panel."