title: graph-tool - k-shortest path - boost::coroutine was not found at compile-time
body: <p>I am trying to find the k shortest paths between two nodes in my directed graph. To this end I run the following snippet of code:</p>
  
  <pre><code>g = load_graph('graph.xml')
  source = find_vertex(g,g.vp.xrn, '774123')
  source = source[0]
  target = find_vertex(g,g.vp.xrn,'636131')
  target = target[0]
  for path in all_shortest_paths(g,source,target):
    print path
  </code></pre>
  
  <p>This returns the following error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/usr/lib/python2.7/dist-packages/graph_tool/topology/__init__.py", line 1532, in all_shortest_paths
      _prop("v", g, all_preds_map))
  RuntimeError: This functionality is not available because boost::coroutine was not found at compile-time
  </code></pre>
  
  <p>Any thoughts as to why that might be the case and how I could solve the problem?</p>