This adds a new method launchWithFile on nsIMIMEInfo which takes care of opening
the selected (preferred or default) application on the mime info with a
specified document. defaultDescription is now readonly, and defaultApplication
no longer available.
This also removes the clone method which was unused in the entire tree.
git-svn-id: svn://10.0.0.236/trunk@153118 18797224-902f-48f8-a5cc-f745e15eee43