Automatic merge of T1.6-rc7-38-ge57a7a113 and 13 pull requests

- Pull request #1086 at e10390b: Add Settings Exporter tool (copy settings to INI, etc)
- Pull request #1091 at 2e06f85: Automatic speed control
- Pull request #1104 at 87cdd9f: Handle simple adhesion within the axle module
- Pull request #1115 at 270f22f: Do not activate ETS switch if no suitable cars are attached
- Pull request #1120 at ba3c47f: Automatically Calculate Friction Values if Missing
- Pull request #1121 at 91d2d26: Manually Override Articulation
- Pull request #1130 at 8ae6bb7: Fix F9 points to an incorrect car ID.
- Pull request #1139 at 03c6f8f: Fix for bug https://bugs.launchpad.net/or/+bug/2117357. 
- Pull request #1143 at 71e57d2: Status in Work Orders popup set too fast
- Pull request #1082 at 5845a1a: Allow variable water level in glass gauge
- Pull request #1081 at 689494b: Brake cuts power unification
- Pull request #1124 at fab5457: Built-in PBL2 brake controller
- Pull request #1128 at 58de4c3: Particle Emitter Overhaul

Author: openrails-bot

Source/Orts.Simulation/Simulation/RollingStocks/SubSystems/PowerTransmissions/Axle.cs

@@ -1100,7 +1100,7 @@ public void Save(BinaryWriter outf)
         /// </summary>
         public (double accelMpSS, double angSpeedRadpS, double driveForceN, double axleMotiveForceN, double axleBrakeForceN, double axleFrictionForceN) GetAxleMotionVariation(double axleSpeedMpS, double elapsedClockSeconds)
         {
-            if (double.IsNaN(axleSpeedMpS)) axleSpeedMpS = 0;
+            if (double.IsNaN(axleSpeedMpS)) axleSpeedMpS = 0; // TODO: axleSpeedMpS should always be a number, find the cause of the NaN
             double slipSpeedMpS = axleSpeedMpS - TrainSpeedMpS;
             // Compute force transmitted to rail according to adhesion curves
             double axleOutForceN;
@@ -1306,8 +1306,8 @@ void Integrate(float elapsedClockSeconds)
         /// <param name="elapsedSeconds"></param>
         public virtual void Update(float elapsedSeconds)
         {
-            if (float.IsNaN(TrainSpeedMpS)) TrainSpeedMpS = 0;
-            if (double.IsNaN(AxleSpeedMpS)) AxleSpeedMpS = 0;
+            if (float.IsNaN(TrainSpeedMpS)) TrainSpeedMpS = 0; // TODO: TrainSpeedMpS should always be a number, find the cause of the NaN
+            if (double.IsNaN(AxleSpeedMpS)) AxleSpeedMpS = 0; // TODO: AxleSpeedMpS should always be a number, find the cause of the NaN
 
             bool advancedAdhesion = Car is MSTSLocomotive locomotive && locomotive.AdvancedAdhesionModel;
             advancedAdhesion &= DriveType != AxleDriveType.NotDriven; // Skip integrator for undriven axles to save CPU