clean up spurious usings

OpenRA.Game/Game.cs

@@ -24,6 +24,7 @@ using System.Drawing;
 using System.IO;
 using System.Linq;
 using System.Reflection;
+using System.Text;
 using System.Windows.Forms;
 using OpenRA.FileFormats;
 using OpenRA.GameRules;
@@ -34,7 +35,6 @@ using OpenRA.Support;
 using OpenRA.Traits;
 using Timer = OpenRA.Support.Timer;
 using XRandom = OpenRA.Thirdparty.Random;
-using System.Text;
 
 namespace OpenRA
 {

OpenRA.Game/Network/OrderManager.cs

@@ -23,8 +23,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using OpenRA.FileFormats;
-using OpenRA.Traits;
-using System.Text;
 
 namespace OpenRA.Network
 {

OpenRA.Game/World.cs

@@ -21,7 +21,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.IO;
 using OpenRA.Collections;
 using OpenRA.Effects;
 using OpenRA.FileFormats;