search plugins

So we've got the firefox search plugin now working again at http://libcom.org/notes/search

That one does google, would be good to make a scroogle one as well. Also if we ever get drupal internal search going could make one using that.

This page has a bit about plugins for IE7: http://blogs.msdn.com/ie/archive/2005/09/14/466186.aspx - if that's still true, they'll run on opensearch, so we could potentially make one opensearch plugin (or a google and internal search one) that'll work on all browsers that accept them.