title: Remove Filter with Mapbox GL JS
body: <p>Using Mapbox GL JS 0.39.1, I set a filter on my layer:</p>
  
  <pre><code>map.setFilter('myLayer', ['!=', 'myKey', 'myValue'])
  </code></pre>
  
  <p>I cannot find a way to remove the filter. I would have thought there would be a map.removeFilter... function but have found nothing in the docs or in web searches. I could apply a fake filter (>'') so that it always matches but that seems inefficient. Surely there is a way to remove a filter.</p>
  
  <p>EDIT: I have found that using the following code will achieve what I am trying to accomplish.  Not sure if this is the recommended approach.</p>
  
  <pre><code>map.setFilter('myLayer');
  </code></pre>