title: jQuery panzoom mousescroll and contain invert aren't working
body: <p>I'm working with panzoom, and it's supposed to work with mouse-scroll. Zooming and stuff works, but I am stuck with this:</p>
  
  <p>I need to make the picture stay in its box, so it won't show what is in the background.</p>
  
  <p>I've been googling days and now I'm turning to you guys.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
  &lt;title&gt;Pannutsuumailu&lt;/title&gt;
  &lt;meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /&gt;
  &lt;style type="text/css"&gt;
    body { background: #F5FCFF; color: #333666; }
    section { text-align: center; margin: 50px 0; }
    .panzoom-parent { border: 2px solid #333; }
    .panzoom-parent .panzoom { border: 2px dashed #666; }
    .buttons { margin: 40px 0 0; }
  &lt;/style&gt;
  &lt;script src="../test/jquery.js"&gt;&lt;/script&gt;
  &lt;script src="../dist/jquery.panzoom.js"&gt;&lt;/script&gt;
  &lt;script src="../bower_components/jquery-mousewheel/jquery.mousewheel.js"&gt;&lt;/script&gt;
  
  &lt;/head&gt;
  
  &lt;section id="focal"&gt;
    &lt;div class="panzoom-parent" width="960" height="1000"&gt;
    &lt;div class="panzoom"&gt;
        &lt;img src="enocell.jpg" width="1920" height="1920"&gt;&lt;/img&gt;
    &lt;/div&gt;
    &lt;/div&gt;
    &lt;script&gt;
   (function() {
        var $section = $('#focal');
        var $panzoom = $section.find('.panzoom').panzoom();
        $panzoom.parent().on('mousewheel.focal', function( e ) {
        contain: "invert",
        e.preventDefault();
          var delta = e.delta || e.originalEvent.wheelDelta;
          var zoomOut = delta ? delta &lt; 0 : e.originalEvent.deltaY &gt; 0;
          $panzoom.panzoom('zoom', zoomOut, {
  
            increment: 0.3,
            minScale: 1,
            maxScale: 2,
          });
        });
      })();
    &lt;/script&gt;
  &lt;/section&gt;
  </code></pre>
  
  <p>Thanks for your help!</p>
  
  <p>I have made this by a sample <a href="https://github.com/timmywil/jquery.panzoom/tree/master/demo" rel="nofollow noreferrer">https://github.com/timmywil/jquery.panzoom/tree/master/demo</a>
  with the plugin "Panzoom" (you can find it up there^)</p>
  
  <p>EDIT:
  This should do it, but it doesn't for some reason work for me.</p>
  
  <p>Contain: "invert" - "make sure your panzoom element is bigger or same size than the parent element.", and unless I'm blind, it is.</p>