title: How to use a BGL directed graph as an undirected one (for use in layout algorithm)?
body: <p>I am working on a directed graph (actually a bidirectional one) with Boost.Graph. I'd like to use the layout algorithms that exist (either Kamada-Kawai or Fruchterman-Reingold) but they only accept undirected graphs as parameters.</p>
  
  <p>What is the simplest way to use these layout algorithms ?
  More generally, what's the right way to lure an algorithm into thinking that a directed graph is actually undirected ?</p>
  
  <p>Thanks,
  Benoît</p>