+ # Move the user *src* to *dst* within the Roundcube database. This
+ # should "rename" him in _every_ table where he is referenced.
+ # Roundcube uses foreign keys properly, so we let the ON UPDATE
+ # CASCADE trigger handle most of the work.
+ #
+ # This can fail is *src* does not exist, or if *dst* already exists
+ # before the move. It should also be an error if the destination
+ # domain doesn't exist. But Roundcube doesn't know about domains, so
+ # we let that slide.
+ #
+ # @param src [User] the source user to be moved.
+ #
+ # @param dst [User] the destination user being moved to.
+ #