title: Change displayed month in jQuery datepicker, depending on another datepicker instance
body: <p>I have two datepicker fields, one is '<strong>start date</strong>' the other is '<strong>end_date</strong>'. </p>
  
  <p>I would like to have the feature that, after user selected '<strong>start date</strong>', then the '<strong>end date</strong>' calendar should show by default the month contain the '<strong>start date</strong>'.</p>
  
  <p>Vise versa, if user first select <strong>end date</strong>, the calendar for the <strong>start date</strong> should show the month contain selected <strong>end date</strong>.</p>
  
  <p>how to implement inside jQuery datepicker? What's the datepicker options I should defined?</p>
  
  <pre><code>$("#start_date").datepicker({
    //which datepicker options should put here?
  })
  </code></pre>