Add the ability for users to specify the Google domain to use for the search.
Done per a user request that landed in plugins.guifications.org's spam bin.
/*
* A completely stupid plugin, inspired by a dumb conversation in #gaim
* and needing some light relief from 'real' work.
* Also as a tribute to our fearless project leader.
*
* Copyright (C) 2005-2008 Peter Lawler <bleeter from users.sf.net>