Remove custom Stopwatch wrapper

Remove the redirection (that doesn't offer any new functionality)
and replace it with the familiar System.Diagnostics.Stopwatch.

OpenRA.Game/Game.cs

@@ -10,6 +10,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Drawing;
 using System.IO;
 using System.Linq;
@@ -484,7 +485,7 @@ namespace OpenRA
 			{
 				if (Settings.Graphics.CapFramerate)
 				{
-					var sw = new Stopwatch();
+					var sw = Stopwatch.StartNew();
 
 					Tick(orderManager);
 

OpenRA.Game/OpenRA.Game.csproj

@@ -291,7 +291,6 @@
     <Compile Include="Primitives\PriorityQueue.cs" />
     <Compile Include="Primitives\Set.cs" />
     <Compile Include="Support\Log.cs" />
-    <Compile Include="Support\Stopwatch.cs" />
     <Compile Include="Support\PerfTimer.cs" />
     <Compile Include="Exts.cs" />
     <Compile Include="Hotkey.cs" />

OpenRA.Game/Support/PerfHistory.cs

@@ -10,6 +10,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Drawing;
 using OpenRA.Primitives;
 
@@ -106,7 +107,7 @@ namespace OpenRA.Support
 
 	public class PerfSample : IDisposable
 	{
-		readonly Stopwatch sw = new Stopwatch();
+		readonly Stopwatch sw = Stopwatch.StartNew();
 		readonly string Item;
 
 		public PerfSample(string item)

OpenRA.Game/Support/PerfTimer.cs

@@ -9,6 +9,7 @@
 #endregion
 
 using System;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 
@@ -16,7 +17,7 @@ namespace OpenRA.Support
 {
 	public class PerfTimer : IDisposable
 	{
-		readonly Stopwatch sw = new Stopwatch();
+		readonly Stopwatch sw = Stopwatch.StartNew();
 		readonly string Name;
 
 		//

OpenRA.Game/Support/Stopwatch.cs

@@ -1,32 +0,0 @@
-#region Copyright & License Information
-/*
- * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
- * This file is part of OpenRA, which is free software. It is made
- * available to you under the terms of the GNU General Public License
- * as published by the Free Software Foundation. For more information,
- * see COPYING.
- */
-#endregion
-
-namespace OpenRA.Support
-{
-	public class Stopwatch
-	{
-		System.Diagnostics.Stopwatch sw;
-
-		public Stopwatch()
-		{
-			Reset();
-		}
-
-		public System.TimeSpan Elapsed
-		{
-			get { return this.sw.Elapsed; }
-		}
-
-		public void Reset()
-		{
-			sw = System.Diagnostics.Stopwatch.StartNew();
-		}
-	}
-}

OpenRA.Game/Traits/Util.cs

@@ -10,6 +10,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using OpenRA.Support;
 
@@ -81,7 +82,7 @@ namespace OpenRA.Traits
 			{
 				var prev = act;
 
-				var sw = new Stopwatch();
+				var sw = Stopwatch.StartNew();
 				act = act.Tick(self);
 				var dt = sw.Elapsed;
 				if (dt > Game.Settings.Debug.LongTickThreshold)

OpenRA.Game/WorldUtils.cs

@@ -10,6 +10,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Drawing;
 using System.Linq;
 using OpenRA.FileFormats;
@@ -173,7 +174,7 @@ namespace OpenRA
 
 		public static void DoTimed<T>(this IEnumerable<T> e, Action<T> a, string text, TimeSpan time)
 		{
-			var sw = new Stopwatch();
+			var sw = Stopwatch.StartNew();
 
 			e.Do(x =>
 			{