added check for img visibility

[kevcenteno]

Here's a sketch in jQuery for checking visibility.

Use case: The image is in a div that is toggled (ie click to show image).

<a id="toggle">toggle</a>
<div id="hidden-img" style="display: none">
  <img class="lazyload" data-src="some-image.jpg" />
</div>

<script>
var lazy = new Riloadr(
  name: 'lazyload',
  defer: {mode: 'invisible'},
  breakpoints: [{name: 'all', minWidth: 0}]
);

$('#toggle').click(function (e) {
  $('#hidden-img').toggle();
  lazy.riload();
}
</script>

[kevcenteno]

@tubalmartin Does this look reasonable?