Sends a new direct message to the specified user from the authenticating user.
sendDM( $screen_name, $text )
The screen name of the recipient user.
In case you want to specify the user ID of the recipient user, you can use Tuitter::sendDMbyId method instead.
The text of your direct message. Keep it under 140 characters.
Returns Tuitter_DM object which has been just sent.