* When converting "anything that looks like a URL" to a real link, first

* When converting "anything that looks like a URL" to a real link, first
  make sure that it isn't already inside a link.  This fixes most of the
  long, ugly URL strings sent by eBay.
* Automatically dismantle mailto: links in HTML messages, and convert
  them to WebCit mail links (clicking on it sends the user to the Mail
  room and begins composing a new message with the recipient and subject
  fields pre-populated).