title: include tracking number in emails subject part
body: <p>As we send shippment emails to customers, in this shippment email, we get tracking number from track.phtml and now the subject part of the email is like, order number and shippment number. I would like to change the subject of the email in which we are senidng as shippment emails. The subject has to be with tracking number. For order number we can get with "order.increment_id", But I dont know how to get the tracking number. SO how can I display tracking number in subject of email?</p>