Gives filters proper names, updates airlocks to use filters

Docking ports still don't use filters though, as it would mess with the
docking ports that are also airlocks. Docking is infrequent though so it
should be fine.

code/game/machinery/embedded_controller/airlock_controllers.dm

@@ -1,6 +1,7 @@
 //base type for controllers of two-door systems
 /obj/machinery/embedded_controller/radio/airlock
 	// Setup parameters only
+	radio_filter = RADIO_AIRLOCK
 	var/tag_exterior_door
 	var/tag_interior_door
 	var/tag_airpump

code/game/machinery/embedded_controller/airlock_program.dm

@@ -265,7 +265,7 @@
 	var/datum/signal/signal = new
 	signal.data["tag"] = tag
 	signal.data["command"] = command
-	post_signal(signal)
+	post_signal(signal, RADIO_AIRLOCK)
 
 /datum/computer/file/embedded_program/airlock/proc/signalPump(var/tag, var/power, var/direction, var/pressure)
 	var/datum/signal/signal = new

code/game/machinery/embedded_controller/embedded_controller_base.dm

@@ -49,6 +49,7 @@
 	//var/radio_power_use = 50 //power used to xmit signals
 
 	var/frequency = 1379
+	var/radio_filter = null
 	var/datum/radio_frequency/radio_connection
 	unacidable = 1
 
@@ -64,15 +65,15 @@
 	else
 		icon_state = "airlock_control_off"
 
-/obj/machinery/embedded_controller/radio/post_signal(datum/signal/signal)
+/obj/machinery/embedded_controller/radio/post_signal(datum/signal/signal, var/filter = null)
 	signal.transmission_method = TRANSMISSION_RADIO
 	if(radio_connection)
 		//use_power(radio_power_use)	//neat idea, but causes way too much lag.
-		return radio_connection.post_signal(src, signal)
+		return radio_connection.post_signal(src, signal, filter)
 	else
 		del(signal)
 
 /obj/machinery/embedded_controller/radio/proc/set_frequency(new_frequency)
 	radio_controller.remove_object(src, frequency)
 	frequency = new_frequency
-	radio_connection = radio_controller.add_object(src, frequency)
+	radio_connection = radio_controller.add_object(src, frequency, radio_filter)