Atmos machine update

Takes a pass at updating ATMOSPHERICS to take advantage of the new powernet changes.

Also removes var/on definitions from many atmos machines. Machines generally shouldn't
be doing "on" things if they aren't using power, and most players don't expect a machine
to use power if it isn't "on," so I guess this is fair game.

Also, further refactoring.

code/modules/admin/verbs/debug.dm

@@ -1007,7 +1007,7 @@ But you can call procs that are of type /mob/living/carbon/human/proc/ for that
 					Pump.air2.gas["nitrogen"] = 3750	//The contents of 2 canisters.
 					Pump.air2.temperature = 50
 					Pump.air2.update_values()
-				Pump.on=1
+				Pump.use_power=1
 				Pump.target_pressure = 4500
 				Pump.update_icon()
 

code/modules/recycling/disposal.dm

@@ -364,7 +364,7 @@
 
 	if(mode != 1) //if off or ready, no need to charge
 		update_use_power(1)
-	else if(air_contents.return_pressure() >= SEND_PRESSURE) 
+	else if(air_contents.return_pressure() >= SEND_PRESSURE)
 		mode = 2 //if full enough, switch to ready mode
 		update()
 	else
@@ -383,11 +383,8 @@
 		var/transfer_moles = (PUMP_MAX_FLOW_RATE/env.volume)*env.total_moles	//group_multiplier is divided out here
 		power_draw = pump_gas(src, env, air_contents, transfer_moles, active_power_usage)
 
-	if (power_draw < 0)
-		//update_use_power(0)
-		use_power = 1	//don't force update - easier on CPU
-	else
-		handle_power_draw(power_draw)
+	if (power_draw > 0)
+		use_power(power_draw)
 
 // perform a flush
 /obj/machinery/disposal/proc/flush()