title: add a drag behaviour on a cubism graph
body: <p>cubism.js is probably meant for realtime vizualizations, not really for interaction, yet I was trying to be able to visualize a large dataset (for example >> 1000points) on the page, without increasing the step or chunking the data</p>
  
  <p>Example: <a href="http://jsfiddle.net/B2WJM/4/" rel="nofollow">http://jsfiddle.net/B2WJM/4/</a> (the first 500 points of a 4000 points dataset are drawn)</p>
  
  <pre><code>var context = cubism.context()
      .step(6e4)
      .size(500)
      .stop();
  </code></pre>
  
  <p>So the idea would be to drag, or zoom this graph using d3 <a href="https://github.com/mbostock/d3/wiki/Zoom-Behavior" rel="nofollow">https://github.com/mbostock/d3/wiki/Zoom-Behavior</a>, hoping there's a nice solution possible by changing dynamically the start and stop attributes</p>