Bug fix for https://bugs.launchpad.net/or/+bug/2047300 Dynamic tracks disappear after long tunnel

Author: Csantucci

Source/RunActivity/Viewer3D/DynamicTrack.cs

@@ -707,6 +707,17 @@ public static PitchControls GetPitchControl(string sPitchControl)
 
             }
         }
+
+        /// <summary>
+        /// Marks the generic track profile, so that its textures never get deleted
+        /// </summary>
+        [CallOnThread("Loader")]
+        public void Mark()
+        {
+            foreach (LOD lod in LODs)
+                lod.Mark();
+        }
+
     }
 
     public class LOD

Source/RunActivity/Viewer3D/World.cs

@@ -116,6 +116,8 @@ public void Load()
                     Precipitation.Mark();
                     Terrain.Mark();
                     Scenery.Mark();
+                    Viewer.TRP?.TrackProfile?.Mark();
+                    Viewer.TRP?.TrackProfileTun?.Mark();
                     Trains.Mark();
                     RoadCars.Mark();
                     Containers.Mark();