Revert "Remove conflict in Sounds.cs"

This reverts commit d58af26.

Author: peternewell

Source/RunActivity/Viewer3D/Sound.cs

@@ -40,19 +40,20 @@
 //#define DEBUGSCR
 
 using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
 using Orts.Common;
 using Orts.Formats.Msts;
 using Orts.Simulation;
 using Orts.Simulation.AIs;
 using Orts.Simulation.Physics;
 using Orts.Simulation.RollingStocks;
 using Orts.Simulation.Signalling;
+using Orts.Viewer3D;
 using ORTS.Common;
 using ORTS.Settings;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.IO;
-using System.Linq;
 using Event = Orts.Common.Event;
 using Events = Orts.Common.Events;