add ability to suppress masterserver pings via Settings (in prep for pchote's new UI magic for this)

OpenRA.Game/Game.cs

@@ -154,7 +154,7 @@ namespace OpenRA
 		internal static void CreateServer()
 		{
 			// todo: LobbyInfo is the wrong place for this.
-			Server.Server.ServerMain(Settings.GameName, Settings.ListenPort, 
+			Server.Server.ServerMain(Settings.InternetServer, Settings.GameName, Settings.ListenPort, 
 				Settings.ExternalPort, LobbyInfo.GlobalSettings.Mods);
 
 			JoinServer(IPAddress.Loopback.ToString(), Settings.ListenPort);

OpenRA.Game/GameRules/UserSettings.cs

@@ -48,6 +48,7 @@ namespace OpenRA.GameRules
 		public readonly string GameName = "OpenRA Game";
 		public readonly int ListenPort = 1234;
 		public readonly int ExternalPort = 1234;
+		public readonly bool InternetServer = true;
 		
 		// Gameplay options
 		// TODO: These need to die

OpenRA.Game/Server/Server.cs

@@ -50,9 +50,11 @@ namespace OpenRA.Server
 		const int MasterPingInterval = 60 * 3;	// 3 minutes. server has a 5 minute TTL for games, so give ourselves a bit
 												// of leeway.
 		static int lastPing = 0;
+		static bool isInternetServer;
 
-		public static void ServerMain(string name, int port, int extport, string[] mods)
+		public static void ServerMain(bool internetServer, string name, int port, int extport, string[] mods)
 		{
+			isInternetServer = internetServer;
 			listener = new TcpListener(IPAddress.Any, port);
 			initialMods = mods;
 			Name = name;
@@ -556,7 +558,7 @@ namespace OpenRA.Server
 
 		static void PingMasterServer()
 		{
-			if (wc.IsBusy) return;
+			if (wc.IsBusy || !isInternetServer) return;
 
 			wc.DownloadDataAsync(new Uri(
 				"http://open-ra.org/master/ping.php?port={0}&name={1}&state={2}&players={3}&mods={4}&map={5}".F(