Feature request: Graph theory loops, weighted edges

[GraxCode]

Hello. I would like to animate several algorithms used in computer science. I've noticed it is not possible to add loop edges (edge from a node to itself) and it is not possible to assign weights to edges (decimal numbers). Can you add this functionality?

[JustinStrik]

Would you like to open this issue and work on it together? I think this would be a great subject to contribute to!