title: Jquery when date change, change another date
body: <p>I use a Jquery date-picker for a start and end date, what I would like to do is when the user changes the 'start' date, the 'end' date automatically changes to the start date + X days?  </p>
  
  <p>What would others suggest the best way of doing this?  I am using GB dates so its <code>dd/mm/yyyy</code> so doesn't work out of the box with the JavaScript date object?  am sure this is trivial for a more experienced jQuery folk!</p>