Fix breathing once and for all (#1996)

* Fix breathing

* WIP changes because I don't trust git stash after 2 weeks

* My imports

* Add gasping, adjust breathing values and fix test

* Make the gasp message appear to others

* Add PopupMessageEveryone extension

* Change used percentage to use a single number instead

* Remove unnecessary logging

* Fix air consistency test

* Add test map to SkippedMaps array

Content.Shared/Atmos/Atmospherics.cs

@@ -217,6 +217,17 @@
         ///     See <see cref="AtmosDirection"/> on the server.
         /// </summary>
         public const int Directions = 4;
+
+        /// <summary>
+        ///     The normal body temperature in degrees Celsius.
+        /// </summary>
+        public const float NormalBodyTemperature = 37f;
+
+        public const float HumanNeededOxygen = MolesCellStandard * BreathPercentage * 0.16f;
+
+        public const float HumanProducedOxygen = HumanNeededOxygen * 0.75f;
+
+        public const float HumanProducedCarbonDioxide = HumanNeededOxygen * 0.25f;
     }
 
     /// <summary>