fixes reconcile_air(); makes gas flow properly through pipes

code/ATMOSPHERICS/datum_pipeline.dm

@@ -195,8 +195,8 @@ var/pipenetwarnings = 10
 	var/list/datum/pipeline/PL = list()
 	PL += src
 
-	for(var/i=1;i<=PL.len;i++)
-		var/datum/pipeline/P = PL[i]
+	for(var/i in PL)
+		var/datum/pipeline/P = i
 		GL += P.air
 		GL += P.other_airs
 		for(var/obj/machinery/atmospherics/components/binary/valve/V in P.other_atmosmch)
@@ -209,18 +209,18 @@ var/pipenetwarnings = 10
 
 	var/total_thermal_energy = 0
 	var/total_heat_capacity = 0
-	var/datum/gas_mixture/total_gas_mixture = new
+	var/datum/gas_mixture/total_gas_mixture = new(0)
 
-	for(var/datum/gas_mixture/G in GL)
+	for(var/i in GL)
+		var/datum/gas_mixture/G = i
 		total_gas_mixture.volume += G.volume
+
 		total_gas_mixture.merge(G)
+
 		total_thermal_energy += G.thermal_energy()
 		total_heat_capacity += G.heat_capacity()
 
-	if(total_heat_capacity > 0)
-		total_gas_mixture.temperature = total_thermal_energy/total_heat_capacity
-	else
-		total_gas_mixture.temperature = 0
+		total_gas_mixture.temperature = total_heat_capacity ? total_thermal_energy/total_heat_capacity : 0
 
 	if(total_gas_mixture.volume > 0)
 		//Update individual gas_mixtures by volume ratio
@@ -229,3 +229,4 @@ var/pipenetwarnings = 10
 			var/list/G_gases = G.gases
 			for(var/id in G_gases)
 				G_gases[id][MOLES] *= G.volume/total_gas_mixture.volume
+

code/LINDA/LINDA_turf_tile.dm

@@ -219,15 +219,11 @@
 /turf/simulated/proc/update_visuals()
 	var/list/new_overlay_types = tile_graphic()
 
-	for(var/overlay in atmos_overlay_types)
-		if(overlay in new_overlay_types)
-			continue //doesn't remove overlays that would only be added
+	for(var/overlay in atmos_overlay_types-new_overlay_types) //doesn't remove overlays that would only be added
 		overlays -= overlay
 		atmos_overlay_types -= overlay
 
-	for(var/overlay in new_overlay_types)
-		if(overlay in atmos_overlay_types)
-			continue //doesn't add overlays that already exist
+	for(var/overlay in new_overlay_types-atmos_overlay_types) //doesn't add overlays that already exist
 		overlays += overlay
 
 	atmos_overlay_types = new_overlay_types

code/__DEFINES/atmospherics.dm

@@ -15,8 +15,8 @@
 //this is kinda hacky... but it means I don't have to change every single time they're called.
 #define SPECIFIC_HEAT	GAS_META][1
 #define GAS_NAME		GAS_META][2
-#define GAS_OVERLAY		GAS_META][3
-#define MOLES_VISIBLE	GAS_META][4
+#define GAS_OVERLAY		GAS_META][4
+#define MOLES_VISIBLE	GAS_META][3
 
 //stuff you should probably leave well alone!
 //ATMOS

code/datums/gas_mixture.dm

@@ -174,7 +174,6 @@ var/list/cached_gases_list = null
 					//Prevents whatever mechanism is causing it to hit negative temperatures.
 				//world << "post [temperature], [procgases["plasma"][MOLES]], [procgases["co2"][MOLES]]
 			*/
-
 	fuel_burnt = 0
 	if(temperature > FIRE_MINIMUM_TEMPERATURE_TO_EXIST)
 		//world << "pre [temperature], [procgases["o2"][MOLES]], [procgases["plasma"][MOLES]]"

code/game/machinery/atmoalter/canister.dm

@@ -22,7 +22,7 @@
 	use_power = 0
 	var/release_log = ""
 	var/update_flag = 0
-	var/gas_type
+	var/gas_type = ""
 
 
 /obj/machinery/portable_atmospherics/canister/sleeping_agent
@@ -379,8 +379,9 @@ update_flag
 	return 1
 
 /obj/machinery/portable_atmospherics/canister/proc/create_gas()
-	air_contents.assert_gas(gas_type)
-	air_contents.gases[gas_type][MOLES] = (src.maximum_pressure*filled)*air_contents.volume/(R_IDEAL_GAS_EQUATION*air_contents.temperature)
+	if(gas_type)
+		air_contents.assert_gas(gas_type)
+		air_contents.gases[gas_type][MOLES] = (src.maximum_pressure*filled)*air_contents.volume/(R_IDEAL_GAS_EQUATION*air_contents.temperature)
 
 //Dirty way to fill room with gas. However it is a bit easier to do than creating some floor/engine/n2o -rastaf0