Add an edge to this graph editor and render it from the given
tail node to an autonomous site at the given location. Give the
new edge the given semanticObject. The "end" flag is either
HEAD_END or TAIL_END, from diva.canvas.connector.ConnectorEvent.
GraphException - If the connector target cannot return a
valid site on the node's figure.
Draw the edge and add it to the layer, establishing
a two-way correspondence between the model and the
view. If the edge already has been associated with some figure in
the view, then use any information in that figure to help draw the
Set the target used to find sites on nodes to connect to. This
sets the local connector target (which is often used to find the
starting point of an edge) and the manipulator's connector target, which
is used after the connector is being dragged.