Automatic merge of T1.5.1-757-gef6c1a8c8 and 16 pull requests

- Pull request #570 at 3539862: Experimental glTF 2.0 support with PBR lighting
- Pull request #839 at d00beb9: First phase of https://blueprints.launchpad.net/or/+spec/additional-cruise-control-parameters
- Pull request #874 at f8dbeab: Dynamic brake controller refactoring
- Pull request #875 at 43bf33e: Bug fix for https://bugs.launchpad.net/or/+bug/2036346 Player train switching doesn't work with 3D cabs
- Pull request #876 at f92de76: docs: add source for documents previously on website to source Documentation folder
- Pull request #882 at a055bca: Blueprint/train car operations UI window
- Pull request #885 at d9ce84b: feat: Add notifications to Menu
- Pull request #886 at 6c0785b: Scene viewer extension to TrackViewer
- Pull request #888 at b20b888: docs: Document player application model
- Pull request #892 at 1f5ba4c: Signal Function OPP_SIG_ID_TRAINPATH
- Pull request #893 at bf8876b: Signal errors
- Pull request #894 at 5ff1e73: Correct Decrease Colour
- Pull request #896 at 5866028: First implementation of https://blueprints.launchpad.net/or/+spec/specific-sounds-for-ai-trains
- Pull request #897 at 0a9d939: feat: Improved system information collection
- Pull request #898 at e271395: Extra line with all the arguments for debugging purposes in logfile
- Pull request #899 at 549ca09: Duplex steam engines - Booster Engine addition

Author: openrails-bot

Source/Orts.Simulation/Simulation/RollingStocks/MSTSSteamLocomotive.cs

@@ -2198,6 +2198,7 @@ public override void Update(float elapsedClockSeconds)
             MotiveForceN = 0;
             CylinderSteamUsageLBpS = 0;
             CylCockSteamUsageLBpS = 0;
+            MeanEffectivePressurePSI = 0;
 
             for (int i = 0; i < SteamEngines.Count; i++)
             {
@@ -2273,10 +2274,12 @@ public override void Update(float elapsedClockSeconds)
                 CumulativeCylinderSteamConsumptionLbs += SteamEngines[i].CylinderSteamUsageLBpS * elapsedClockSeconds;
                 CylinderSteamUsageLBpS += SteamEngines[i].CylinderSteamUsageLBpS;
                 CylCockSteamUsageLBpS += SteamEngines[i].CylCockSteamUsageLBpS;
-                
-
-                SteamEngines[i].MeanEffectivePressurePSI = MeanEffectivePressurePSI;
 
+                if (SteamEngines[i].MeanEffectivePressurePSI > MeanEffectivePressurePSI)
+                {
+                    MeanEffectivePressurePSI = SteamEngines[i].MeanEffectivePressurePSI;
+                }
+                
                 SteamEngines[i].TractiveForceN = 0;
 
                 float tractiveforcethrottle = 0;
@@ -4899,6 +4902,11 @@ private void UpdateCylinders(float elapsedClockSeconds, float throttle, float cu
                 SteamEngines[numberofengine].MeanEffectivePressurePSI = TotalWorkInLbs / Me.ToIn(SteamEngines[numberofengine].CylindersStrokeM); // MEP doen't need to be converted from Atm to gauge pressure as it is a differential pressure.
                 SteamEngines[numberofengine].MeanEffectivePressurePSI = MathHelper.Clamp(SteamEngines[numberofengine].MeanEffectivePressurePSI, 0, MaxBoilerPressurePSI); // Make sure that Cylinder pressure does not go negative
 
+                if (throttle < 0.01)
+                {
+                    SteamEngines[numberofengine].MeanEffectivePressurePSI = 0;
+                }
+
 #if DEBUG_LOCO_STEAM_MEP
                 if (DebugWheelRevs >= 55.0 && DebugWheelRevs < 55.1 | DebugWheelRevs >= 110.0 && DebugWheelRevs < 110.1 | DebugWheelRevs >= 165.0 && DebugWheelRevs < 165.05 | DebugWheelRevs >= 220.0 && DebugWheelRevs < 220.05)
                  {