/// <summary>
/// Creates Core edge and related Visual edge.
/// </summary>
/// <param name="v1">Endpoint of creating edge.</param>
/// <param name="v2">Endpoint of creating edge.</param>
public Edge CreateEdge(Vertex v1, Vertex v2)
{
Edge e = new Edge(v1, v2);
Edges.Add(e);
v1.Edges.Add(e);
v2.Edges.Add(e);
visual.CreateVisualEdge(e);
return(e);
}
