First pass at a generic reusable command line option parser.

lib/args/utils.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// TODO(rnystrom): This file was copied from pub.
+/** Generic utility functions. Stuff that should possibly be in core. */
+#library('args_utils');
+
+/** Pads [source] to [length] by adding spaces at the end. */
+String padRight(String source, int length) {
+  final result = new StringBuffer();
+  result.add(source);
+
+  while (result.length < length) {
+    result.add(' ');
+  }
+
+  return result.toString();
+}