convert FileExtractor into a Utility cmdlet

OpenRA.Utility/Program.cs

@@ -25,6 +25,7 @@ namespace OpenRA.Utility
 				{ "--shp", Command.ConvertPngToShp },
 				{ "--png", Command.ConvertShpToPng },
 				{ "--fromd2", Command.ConvertFormat2ToFormat80 },
+				{ "--extract", Command.ExtractFiles },
 			};
 
 			if (args.Length == 0) { PrintUsage(); return; }
@@ -57,6 +58,7 @@ namespace OpenRA.Utility
 			Console.WriteLine("  --settings-value KEY             Get value of KEY from settings.yaml");
 			Console.WriteLine("  --shp PNGFILE FRAMEWIDTH         Convert a PNG containing one or more frames to a SHP");
 			Console.WriteLine("  --png SHPFILE PALETTE            Convert a SHP to a PNG containing all of its frames");
+			Console.WriteLine("  --extract MOD[,MOD]* FILES	      Extract files from mod packages");
 		}
 
 		static T WithDefault<T>(T def, Func<T> f)