Explore supporting non-line graphs

[openjck]

These notes are based on my meeting with Rob Miller yesterday.

We don't need to support every possible kind of visualization, but it may be good to support a few additional basic types like bar charts, pie graphs, and tables. These appear to be popular on STMO. That said, I'd like to verify this for myself. I'd like to prioritize the visualization types that are most popular on STMO.

We ideally want to change as little as possible, but we can consider switching to a different charting library like Plotly or Chart.js if it would make our work significantly easier.

This will start as exploratory work. We're most interested in how easy it is to add support for new visualization types.

[openjck]

Here's a great comparison of different charting libraries:

https://blog.sicara.com/compare-best-javascript-chart-libraries-2017-89fbe8cb112d