Automatic merge of T1.5.1-1695-gade019506 and 17 pull requests

- Pull request #570 at f4a7495: glTF 2.0 support with PBR lighting
- Pull request #900 at 4629736: DMI in 3D cab + two more dials
- Pull request #1030 at d3ae4a2: Refactor settings, in prep for settings exporter
- Pull request #1045 at cc4d53c: Bugfix: Empty Start Time for Explore, and other issues loading from Menu Selection and Content Routes
- Pull request #1052 at 5bbc476: Content Manager: Add axle count, and lowest derail force
- Pull request #1062 at de91cc4: Train Forces popup Window.
- Pull request #1064 at 9b3415e: Add Train Info tab to Help window (F1)
- Pull request #1066 at 62c89c1: Log derailment, using TraceInformation.
- Pull request #892 at 1f5ba4c: Signal Function OPP_SIG_ID_TRAINPATH
- Pull request #1000 at d8d9709: Locomotive operation from control car
- Pull request #1029 at 92c74ef: Superelevation Follow Up Fixes
- Pull request #1057 at 50c3789: Switchable brake system
- Pull request #1069 at 3f153f0: Mouse wheel control only with Alt – Followup for #1051
- Pull request #1070 at 3a66597: Fix a NullReferenceException in TCS scripts
- Pull request #1055 at f6bf9fa: Route Based TTrack Sounds
- Pull request #896 at f1681df: First implementation of https://blueprints.launchpad.net/or/+spec/specific-sounds-for-ai-trains
- Pull request #1049 at 4dd8c4f: Re-organise document storage and access

Author: openrails-bot

Source/RunActivity/Viewer3D/Popups/TrainForcesWindow.cs

@@ -94,13 +94,16 @@ public class TrainForcesWindow : Window
         private int LastPlayerTrainCars;
         private bool LastPlayerLocomotiveFlippedState;
 
-        private float LimitForCouplerStrengthN = 2.2e6f;  // 500k lbf, used for graph scale only
+        private static readonly float HighestRealisticCouplerStrengthN = 2.2e6f;  // 500k lbf, used for graph scale only
+        private float LimitForCouplerStrengthN = HighestRealisticCouplerStrengthN;
         private float CouplerStrengthScaleN;
 
-        private float LimitForDerailForceN = 1.55e5f;  // 35k lbf, used for graph scale only
+        private static readonly float HighestRealisticDerailForceN = 1.55e5f;  // 35k lbf, used for graph scale only
+        private float LimitForDerailForceN = HighestRealisticDerailForceN;
         private float DerailForceScaleN;
 
-        private float LimitForBrakeForceN = 2.0e5f;  // 45k lbf, used for graph scale only
+        private static readonly float HighestRealisticBrakeForceN = 2.0e5f;  // 45k lbf, used for graph scale only
+        private float LimitForBrakeForceN = HighestRealisticBrakeForceN;
         private float BrakeForceScaleN;
 
         private Image[] CouplerForceBarGraph;
@@ -312,9 +315,9 @@ public override void PrepareFrame(ElapsedTime elapsedTime, bool updateFull)
         /// </summary>
         private void SetConsistProperties(Train theTrain)
         {
-            float lowestCouplerBreakN = LimitForCouplerStrengthN;
-            float lowestDerailForceN = LimitForDerailForceN;
-            float lowestMaxBrakeForceN = LimitForBrakeForceN;
+            float lowestCouplerBreakN = HighestRealisticCouplerStrengthN;
+            float lowestDerailForceN = HighestRealisticDerailForceN;
+            float lowestMaxBrakeForceN = HighestRealisticBrakeForceN;
 
             foreach (var car in theTrain.Cars)
             {