Removed unused using directives.

OpenRA.Test/OpenRA.Game/ActorInfoTest.cs

@@ -9,9 +9,7 @@
  */
 #endregion
 
-using System;
 using System.Linq;
-using System.Text.RegularExpressions;
 using NUnit.Framework;
 using OpenRA.Traits;
 

OpenRA.Test/OpenRA.Game/CPosTest.cs

@@ -1,5 +1,4 @@
-using System.Runtime.Remoting.Metadata;
-using NUnit.Framework;
+using NUnit.Framework;
 
 namespace OpenRA.Test
 {

OpenRA.Test/OpenRA.Game/VariableExpressionTest.cs

@@ -9,10 +9,8 @@
  */
 #endregion
 
-using System;
 using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using NUnit.Framework;
 using OpenRA.Support;