I really want to be able to plot trees without graphviz. Plotting trees is important. Even with conda (good luck without) this keeps creating issues on windows.

I think we should add a function that directly plots a tree without going through the graphviz file format. Plotting trees is much easier than plotting general graphs, and so I think we can get a decent-looking 80/20 solution for this relatively quickly.

We could technically support some fancy js output for jupyter, but I think as a first step "just" having a pure matplotlib version would be amazing.