Tweaked welding:

Welders that are on but not in use use fuel more slowly than before, when actively welding, fuel use rate increases to roughly 4 times what the previous rate was. This allows for an average of 4 regular walls to be cut through before refueling is needed, based on my testing. Shorter-length welding tasks will allow for more uses between refuels.

Also cleaned up a few things that still used the "click welder at thing, lose x units of fuel" code.

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@1403 316c924e-a436-60f5-8080-3fe189b3f50e

code/ATMOSPHERICS/components/unary/vent_pump.dm

@@ -246,6 +246,7 @@
 	attackby(obj/item/W, mob/user)
 		if(istype(W, /obj/item/weapon/weldingtool) && W:welding)
 			if (W:remove_fuel(0,user))
+				W:welding = 2
 				user << "\blue Now welding the vent."
 				if(do_after(user, 20))
 					playsound(src.loc, 'Welder2.ogg', 50, 1)
@@ -255,6 +256,7 @@
 					else
 						user.visible_message("[user] unwelds the vent.", "You unweld the vent.", "You hear welding.")
 						welded = 0
+				W:welding = 1
 			else
 				user << "\blue You need more welding fuel to complete this task."
 				return 1