title: Jquery datepicker beforeShowDay after initializing
body: <p>When I am setting beforeShowDay after initializing it doesn't work</p>
  
  <pre><code>$("#dater").datepicker();
  
  $("#dater").datepicker({
      beforeShowDay: renderCalendarCallback
  });
  </code></pre>
  
  <p>It will work when I will change and call beforeShowDay for first time</p>
  
  <pre><code>$("#dater").datepicker({
      beforeShowDay: renderCalendarCallback
  });
  
  $("#dater").datepicker();
  </code></pre>
  
  <p>How can I fix this to call beforeShowDay in first scenario too? Note that I can't remove first initialization, because it is unreachable for me. You can test this scenarios in this jsfiddle <a href="http://jsfiddle.net/b6V3W/352/" rel="noreferrer">http://jsfiddle.net/b6V3W/352/</a></p>