Able to read edge from undirected edgeset
Graph reader and graph writer can resolve items by id.

It makes possible:

GraphReader<Graph> reader(std::cin, graph);

reader.readNodeMap....

NewEdgeSetAdaptor<Graph> edgeset(graph);
UndirEdgeSetReader<Graph> unir_edgeset_reader(reader, edgeset, reader);

reader.run();

It reads the graph and an additional edgeset in to the edgeset.