[Feature request] Sankey Diagram Support

[Funtime60]

I have found that it is VERY hard to actually design my Py+Al factories without the sankey diagrams like those provided by factoriolab. (It's a shame that their preset for Py+Al crashes when you try to add any item). It'd be great if the ability to either generate a diagram internally or export diagram instructions for an external tool could be added. Thanks.