removing unnecessary edge_iterator
Renaming Graph to GraphWD, adding tests.
graph.hpp renamed to graphwd.hpp
Graph stands for not weighed, not directed graph.
new graph_xml.hpp file to read (with libxml/parser) and write to XML
priority_queue.hpp with ineffective modifyKey
new function: modifyVertex, internal edgecontainer is a typedef
Qt visualization of graph, from the Elastic Nodes Example
graph has modifyVertex member
qtgraph loads/saves state to graph
small cleanups, itemAt fix with Map