[MIRROR] Fixes exploits and bugs that allowed for infinite pressure&temp atmos. (#9853)

Co-authored-by: Cameron Lennox <killer65311@gmail.com>

code/ZAS/Fire.dm

@@ -318,7 +318,8 @@ If it gains pressure too slowly, it may leak or just rupture instead of explodin
 			zone.remove_liquidfuel(used_liquid_fuel, !check_combustability())
 
 		//calculate the energy produced by the reaction and then set the new temperature of the mix
-		temperature = (starting_energy + vsc.fire_fuel_energy_release * (used_gas_fuel + used_liquid_fuel)) / heat_capacity()
+		if(heat_capacity() > 0)
+			temperature = min((starting_energy + vsc.fire_fuel_energy_release * (used_gas_fuel + used_liquid_fuel)) / heat_capacity(), MAX_ATMOS_TEMPERATURE)
 		update_values()
 
 		#ifdef FIREDBG

code/__defines/atmos.dm

@@ -98,3 +98,4 @@
 // Used in various things like tanks and oxygen pumps.
 #define TANK_MAX_RELEASE_PRESSURE (3*ONE_ATMOSPHERE)
 #define TANK_DEFAULT_RELEASE_PRESSURE ONE_ATMOSPHERE
+#define MAX_ATMOS_TEMPERATURE 1e7 //Without having a max temp, you can get .inf temps

code/modules/xgm/xgm_gas_mixture.dm

@@ -144,7 +144,8 @@
 			return 0
 		var/thermal_energy_limit = -(temperature - TCMB)*heat_capacity	//ensure temperature does not go below TCMB
 		thermal_energy = max( thermal_energy, thermal_energy_limit )	//thermal_energy and thermal_energy_limit are negative here.
-	temperature += thermal_energy/heat_capacity
+	if(heat_capacity > 0)
+		temperature = min(temperature + thermal_energy / heat_capacity, MAX_ATMOS_TEMPERATURE)
 	return thermal_energy
 
 //Returns the thermal energy change required to get to a new temperature