title: Directed, acyclic graph in d3.js
body: <p>Is there a reliable way of drawing directed, acyclic graphs in D3.js today? I'm trying to visualize prerequisites in a curriculum, <a href="http://einstein.franklin.edu/itec/ITEC_Prerequisites_2011.png" rel="noreferrer">similar to this</a>.</p>
  
  <p>I've seen some older answers to similar questions with the most promising lead being <a href="http://bl.ocks.org/mbostock/1138500" rel="noreferrer">this hack</a>, though it doesn't work reliably well with larger and more complex data sets.</p>
  
  <p>Is this simply a rare case of a visualization that D3 is not ideal for?</p>