Repurpose unused Timer.cs and add some loading perf metrics

OpenRA.Game/Support/PerfTimer.cs

@@ -0,0 +1,42 @@
+#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
+
+using System;
+
+namespace OpenRA.Support
+{
+	public class PerfTimer : IDisposable
+	{
+		readonly Stopwatch sw = new Stopwatch();
+		readonly string Name;
+		static System.Threading.ThreadLocal<int> depth = new System.Threading.ThreadLocal<int>();
+
+		public PerfTimer(string name)
+		{
+			this.Name = name;
+			depth.Value++;
+		}
+
+		public void Dispose()
+		{
+			string indentation;
+
+			if (--depth.Value >= 0)
+				indentation = new string('\t', depth.Value);
+			else
+			{
+				depth.Value = 0;
+				indentation = string.Empty;
+			}
+
+			Log.Write("perf", "{0}{1}: {2} ms", indentation, this.Name, Math.Round(this.sw.Elapsed.TotalMilliseconds));
+		}
+	}
+}