title: Graphml parse error : Invalid xmlChar
body: <p>igraph version : 0.6.5<br>
  python version : 2.7.6</p>
  
  <p>I am calculating the Betweenness centrality on a graphml graph dump. But while reading through the <b>Read_GraphML</b> function it throws the following error :</p>
  
  <pre><code>egraph = Graph.Read_GraphML("/path/graph.graphml")
  igraph._igraph.InternalError: Error at foreign-graphml.c:1042: xmlParseCharRef: invalid xmlChar value 55349, Parse error
  </code></pre>
  
  <p>XML namespance seems correct </p>
  
  <pre><code>&lt;?xml version="1.0" ?&gt;&lt;graphml xmlns="http://graphml.graphdrawing.org/xmlns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns http://graphml.graphdrawing.org/xmlns/1.1/graphml.xsd"&gt;
  </code></pre>
  
  <p><br>
  <br>
  Could anyone suggest what could be the problem ? Is it with the graphml?</p>