Add support for dart

Hi Andy,

This patch adds support for restricting the search to dart files.  I just searched for "python" and added "dart" where alphabetically appropriate.  Let me know if there's more places that need to be added.  (I'm not sure what's auto-generated and what isn't.)

Dart is: http://www.dartlang.org/, BTW :)

Regards,
--jrockway