Split the download/install logic into multiple files.

OpenRA.Game/Download.cs

@@ -0,0 +1,61 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2011 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;
+using System.ComponentModel;
+using System.Net;
+
+namespace OpenRA
+{
+	public class Download
+	{
+		WebClient wc;
+		bool cancelled;
+		
+		public Download(string url, string path, Action<DownloadProgressChangedEventArgs> onProgress, Action<AsyncCompletedEventArgs, bool> onComplete)
+		{
+			wc = new WebClient();
+			wc.Proxy = null;
+	
+			wc.DownloadProgressChanged += (_,a) => onProgress(a);
+			wc.DownloadFileCompleted += (_,a) => onComplete(a, cancelled);
+			
+			Game.OnQuit += () => Cancel();
+			wc.DownloadFileCompleted += (_,a) => {Game.OnQuit -= () => Cancel();};
+			
+			wc.DownloadFileAsync(new Uri(url), path); 
+		}
+		
+		public void Cancel()
+		{
+			Game.OnQuit -= () => Cancel();
+			wc.CancelAsync();
+			cancelled = true;
+		}
+		
+		public static string FormatErrorMessage(Exception e)
+		{
+			var ex = e as System.Net.WebException;
+			if (ex == null) return e.Message;
+			
+			switch(ex.Status)
+			{
+				case WebExceptionStatus.NameResolutionFailure:
+				case WebExceptionStatus.Timeout:
+				case WebExceptionStatus.ConnectFailure:
+					return "Cannot connect to remote server";
+				case WebExceptionStatus.ProtocolError:
+					return "File not found on remote server";
+				default:
+					return ex.Message;
+			}
+		}
+	}
+}