INode.Edges cast in INode{} implementation is slow!

[Kemsekov]

This part is really slow

        IEnumerable<IEdge> INode.Edges => this.Edges.Select(n=>n as IEdge);

It will do Select for each edge any time you will try to access Edges property. Because if this current version of library is 3x slower than previous one. Fix it

[Kemsekov]

I fixed it but I had to add extra abstraction level and It is still not perfect solution, so I will rename issue