Fix encoding problems with ZipFile.

Without setting the DefaultCodePage it may cause problems on systems without 866 code page installed.

OpenRA.Game/FileSystem/ZipFile.cs

@@ -10,6 +10,7 @@
 
 using System.Collections.Generic;
 using System.IO;
+using System.Text;
 using ICSharpCode.SharpZipLib.Zip;
 using SZipFile = ICSharpCode.SharpZipLib.Zip.ZipFile;
 
@@ -21,6 +22,11 @@ namespace OpenRA.FileSystem
 		SZipFile pkg;
 		int priority;
 
+		static ZipFile()
+		{
+			ZipConstants.DefaultCodePage = Encoding.Default.CodePage;
+		}
+
 		public ZipFile(string filename, int priority)
 		{
 			this.filename = filename;