||This class is the same as DefaultDirectedGraph but changed to support
multiple edges between two nodes
||A directed graph which is also org.jgrapht.ListenableGraph.
||Graph Listener to set points on edges so that multiple edges between
two nodes can be displayed properly.
||A Sketch represents an EA Sketch diagram used to represent a database, this object
also extends the JGraph swing component, allowing it to be added directly to the