title: Boost::graph undefined properties
body: <p>I am loading a graphviz dot diagram into a Boost::Graph object.  I want to make sure that the nodes and arcs have a set of specific properties but do not care if they have any other properties.  All I want Boost::Graph to do is to flag those (a catchable exception is fine) and not just abort the loading of the file.  </p>
  
  <p>For example, I would like the following two nodes to parse into a vertex structure that contains only "style" and "fillcolor" and ignored any "unknown_tag" tags.</p>
  
  <pre><code>0 [style=filled, fillcolor="Green"]
  1 [style=filled, fillcolor="Green", unknown_tag="fubar"]
  </code></pre>
  
  <p>Is that possible?</p>