Automatic merge of T1.5-rc1-80-gf4212d3c4 and 12 pull requests

- Pull request #570 at 824f96f: Experimental glTF 2.0 support with PBR lighting
- Pull request #630 at 704731a: Sky Color Fix (Addresses Trello Roadmap Card #367 for More accurate sunrise and sunset)
- Pull request #652 at 918fdb1: Add button functions to Raildriver
- Pull request #677 at c1c417f: Correct double heading bug
- Pull request #692 at 20de7da: Italian translation for OR 1.5
- Pull request #699 at 6baf43d: Bug fix for https://bugs.launchpad.net/or/+bug/1987453. Web: HUD/Force Information, some labels not visible.
- Pull request #706 at 265d33d: Extended door functionality
- Pull request #712 at 68cd8ab: Search for NORMAL signals if no argument is provided
- Pull request #713 at 966a61c: https://blueprints.launchpad.net/or/+spec/cruise-control 
- Pull request #715 at 447143b: Bug fix for //bugs.launchpad.net/or/+bug/1990930 Default snow terrtex not appearing
- Pull request #722 at fb9079e: Fix Windows Forms deprecations in ActivityEditor
- Pull request #726 at b6cc020: Correctly initialize triple valve for EP trains

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

@@ -259,11 +259,19 @@ public float TransmissionEfficiency
         public float TrainSpeedMpS;
 
         /// <summary>
-        /// Wheel slip indicator
+        /// Read only wheel slip indicator
         /// - is true when absolute value of SlipSpeedMpS is greater than WheelSlipThresholdMpS, otherwise is false
         /// </summary>
-        public bool IsWheelSlip { get; private set; }
-        float WheelSlipTimeS;
+        public bool IsWheelSlip
+        {
+            get
+            {
+                if (Math.Abs(SlipSpeedMpS) > WheelSlipThresholdMpS) 
+                    return true;
+                else
+                    return false;
+            }
+        }
 
         /// <summary>
         /// Read only wheelslip threshold value used to indicate maximal effective slip
@@ -282,13 +290,18 @@ public float WheelSlipThresholdMpS
         }
 
         /// <summary>
-        /// Wheelslip warning indication
+        /// Read only wheelslip warning indication
         /// - is true when SlipSpeedMpS is greater than zero and 
         ///   SlipSpeedPercent is greater than SlipWarningThresholdPercent in both directions,
         ///   otherwise is false
         /// </summary>
-        public bool IsWheelSlipWarning { get; private set; }
-        float WheelSlipWarningTimeS;
+        public bool IsWheelSlipWarning
+        {
+            get
+            {
+                return Math.Abs(SlipSpeedPercent) > SlipWarningTresholdPercent;
+            }
+        }
 
         /// <summary>
         /// Read only slip speed value in metric meters per second
@@ -540,29 +553,6 @@ public virtual void Update(float timeSpan)
             CompensatedAxleForceN = AxleForceN + Math.Sign(TrainSpeedMpS) * BrakeRetardForceN;
             if (AxleForceN == 0) CompensatedAxleForceN = 0;
 
-            if (Math.Abs(SlipSpeedMpS) > WheelSlipThresholdMpS)
-            {
-                // Wait some time before indicating wheelslip to avoid false triggers
-                if (WheelSlipTimeS > 0.1f)
-                {
-                    IsWheelSlip = IsWheelSlipWarning = true;
-                }
-                WheelSlipTimeS += timeSpan;
-            }
-            else if (Math.Abs(SlipSpeedPercent) > SlipWarningTresholdPercent)
-            {
-                // Wait some time before indicating wheelslip to avoid false triggers
-                if (WheelSlipWarningTimeS > 0.1f) IsWheelSlipWarning = true;
-                IsWheelSlip = false;
-                WheelSlipWarningTimeS += timeSpan;
-            }
-            else
-            {
-                IsWheelSlipWarning = false;
-                IsWheelSlip = false;
-                WheelSlipWarningTimeS = WheelSlipTimeS = 0;
-            }
-
             if (timeSpan > 0.0f)
             {
                 slipDerivationMpSS = (SlipSpeedMpS - previousSlipSpeedMpS) / timeSpan;