Custom default edge/vertex value for Test Graph Generation

[netj]

Can we allow the user to specify a default edge value and/or vertex value when composing a graph? Currently we're simply picking 0 for unspecified vertices, but it would be much nicer to have this value configurable. Having two input boxes next to Directed/Undirected radio input might do it. They will be set to null initially, then become 0 if any value is actually assigned to one of them.

[vikeshkhanna]

Sounds good. Will work on that.