Moves a few vars where they should be

This should reduce the memory usage

code/ATMOSPHERICS/mainspipe.dm

@@ -36,8 +36,6 @@ obj/machinery/atmospherics/mains_pipe
 	icon = 'icons/obj/atmospherics/mainspipe.dmi'
 	layer = 2.4 //under wires with their 2.5
 
-	force = 20
-
 	var/volume = 0
 
 	var/alert_pressure = 80*ONE_ATMOSPHERE

code/ATMOSPHERICS/pipes.dm

@@ -3,7 +3,6 @@
 	var/datum/gas_mixture/air_temporary // used when reconstructing a pipeline that broke
 	var/datum/pipeline/parent
 	var/volume = 0
-	force = 20
 
 	layer = 2.4 //under wires with their 2.44
 	use_power = 0