Removed area.uid var and /area/New()

- var/uid was used in only a handful of places.  Because areas are singletons
  it is safe to replace the uid with \ref, areas don't get deleted.
- And with that /area/New() is empty, we can remove it!

code/ATMOSPHERICS/components/unary/vent_pump.dm

@@ -85,7 +85,7 @@
 
 	icon = null
 	initial_loc = get_area(loc)
-	area_uid = initial_loc.uid
+	area_uid = "\ref[initial_loc]"
 	if (!id_tag)
 		assign_uid()
 		id_tag = num2text(uid)

code/ATMOSPHERICS/components/unary/vent_scrubber.dm

@@ -38,7 +38,7 @@
 
 	icon = null
 	initial_loc = get_area(loc)
-	area_uid = initial_loc.uid
+	area_uid = "\ref[initial_loc]"
 	if (!id_tag)
 		assign_uid()
 		id_tag = num2text(uid)

code/game/area/areas.dm

@@ -40,14 +40,8 @@
 	var/list/forced_ambience = null
 	var/sound_env = STANDARD_STATION
 	var/turf/base_turf //The base turf type of the area, which can be used to override the z-level's base turf
-	var/global/global_uid = 0
-	var/uid
 	var/forbid_events = FALSE // If true, random events will not start inside this area.
 
-/area/New()
-	uid = ++global_uid
-	..()
-
 /area/Initialize()
 	. = ..()
 

code/game/machinery/air_alarm.dm

@@ -116,7 +116,7 @@
 
 /obj/machinery/alarm/proc/first_run()
 	alarm_area = get_area(src)
-	area_uid = alarm_area.uid
+	area_uid = "\ref[alarm_area]"
 	if(name == "alarm")
 		name = "[alarm_area.name] Air Alarm"