title: fullcalendar: how can i get the first and last day of the relevant viewed month (and not the days of of the prev \ next month)
body: <p>i want to know what is the first day and the last day of the main month viewed in fullcalendar.</p>
  
  <p>here is the relevant month view:</p>
  
  <p><a href="https://i.stack.imgur.com/1eNUH.png" rel="noreferrer"><img src="https://i.stack.imgur.com/1eNUH.png" alt="enter image description here"></a></p>
  
  <pre><code>     events: function (start, end, timezone, callback) { //custom events function to be called every time the view changes
            alert (start.format());
            alert (end.format());
       },
  </code></pre>
  
  <p>when i run this code on this month (april 2017), i get:
  start.format()=2017-03-26 
  end.format()= 2017-05-07
  and i would like to get the following dates:
  start: 2017-04-01
  end:  2017-04-30</p>
  
  <p>is there any way for me to get this dates inside the event function?</p>
  
  <p>many thanks</p>
  
  <p>p.s</p>
  
  <p>i would not like to use the "showNonCurrentDates: false" option</p>