Attempt to expand non-local hostnames without dots to valid
www.HOSTNAME.{com,edu,net,org} hosts.  For example, a request of
"http://yahoo/" will search DNS and find www.yahoo.com.  The resulting
URL would then be "http://www.yahoo.com/".

This filter has the following preferences:

* HostnameExpander.defaultDomain

  The name of your local domain which can be used for hosts which
  don't include a domain.

* HostnameExpander.prefix

  Comma separated list of host prefixes to try during expansion.
  The default is: www.,home.,web.,http.

* HostnameExpander.suffix

  Comma separated list of host prefixes to try during expansion.
  The default is: .com,.edu,.net,.org
