title: Google maps api filter checkbox
body: <p>I am trying to make google map with filtering. One filter is select box (for now it is working) and other filer is with check boxes. So now my it have behavior as a radio button. You can se example here <a href="http://extrol.ellectadigital.com/distributeri/" rel="nofollow noreferrer">http://extrol.ellectadigital.com/distributeri/</a>. 
  <br>When you check it, it shows good pin, but when you click on the second it removes the first pin, and I don't want that. 
  So here is my code :   </p>
  
  <pre><code>`http://codepen.io/PoznanM/pen/VpoZOm`
  </code></pre>