Remove secondary AllowPortForward setting.

The global setting is fine, and this simplifies
both the code and the UI.

OpenRA.Game/Server/Server.cs

@@ -134,8 +134,7 @@ namespace OpenRA.Server
 
 			randomSeed = (int)DateTime.Now.ToBinary();
 
-			// UPnP is only supported for servers created by the game client.
-			if (!dedicated && Settings.AllowPortForward)
+			if (UPnP.Status == UPnPStatus.Enabled)
 				UPnP.ForwardPort(Settings.ListenPort, Settings.ExternalPort).Wait();
 
 			foreach (var trait in modData.Manifest.ServerTraits)
@@ -206,7 +205,7 @@ namespace OpenRA.Server
 					if (State == ServerState.ShuttingDown)
 					{
 						EndGame();
-						if (!dedicated && Settings.AllowPortForward)
+						if (UPnP.Status == UPnPStatus.Enabled)
 							UPnP.RemovePortForward().Wait();
 						break;
 					}