title: Plugin event methods in Virtuemart for order status
body: <p>I have my order list in the backend , 
  I want to fire plugin events when order status is changed from Confirmed by Shopper to "Shipped" or "Confirmed"</p>
  
  <p>Already using </p>
  
  <blockquote>
    <p>plgVmConfirmedOrder()</p>
  </blockquote>
  
  <p>Which is for confirmed by shopper, and successful transimission of SMS
  Also </p>
  
  <blockquote>
    <p>plgVmOnShipOrderPayment() Not responding.</p>
  </blockquote>
  
  <p>Any other method or way to do so?  I want this methods for the SMS gateway. </p>