Fix edge indexing bug in condensation_graph()

Edges were not properly indexed after graph generation.

src/graph/community/graph_community_network.cc

@@ -74,4 +74,5 @@ void community_network(GraphInterface& gi, GraphInterface& cgi,
                    vertex_properties(), weight_properties(),
                    ecount_properties())
         (community_property, weight, edge_count);
+     cgi.ReIndexEdges();
 }

src/graph/community/graph_community_network.hh

@@ -73,7 +73,6 @@ struct get_community_network
         for (typeof(comms.begin()) iter = comms.begin(); iter != comms.end();
              ++iter)
         {
-
             cvertex_t cs = comm_vertices[iter->first];
             for (size_t i = 0; i < iter->second.size(); ++i)
             {