handle other clicks on carousel items

Dragging the carousel items can cause a click which can follow a link and/or execute some event handlers. Before, only links were "prevented". This fixes the issue where JS click handlers are still executed when the items are being dragged. This still allows using JS to click the items (`.click()`) even if the items are being dragged.

An example of what should work:
````html
<style>img { width: ...px; }</style>
<div data-ur-set="carousel">
  <div data-ur-carousel-component="scroll_container">
    <div data-ur-carousel-component="item">
      <a href="http://www.google.com/"><img src="..."></a>
    </div>
    <a href="http://www.google.com/" data-ur-carousel-component="item">
      <img src="...">
    </a>
    <img onclick="console.log(event, this);" data-ur-carousel-component="item" src="...">
    <img id="img" data-ur-carousel-component="item" src="...">
  </div>
</div>
<script>
  $(function() { $("#img").click(function() { console.log("img"); }); });
</script>
````
However any click event handlers added before the carousel was initialized will still follow through. This is why the example has a width style on images to prevent the carousel from late-loading (which happens when any item has a zero width).