Moved TRPFile construction code from Simulator to Viewer3D.Initialize so that SceneryMaterials dictionary would exist at time of TRPFile instantiation. Packaged TRPFile construction code as TRPFile.CreateTrackProfile.
Correct the crossing gates so that some will be visible but silent. Adjust the sound volumes so that it can be faded based on distance. Remove gate sound if the gate is unloaded. Add a check of carspawn.dat.