Add support for custom node shapes in react-force-graph

[nielsdejong]

To support an industry standard for biotech visualizations (https://www.ncbi.nlm.nih.gov/glycans/snfg.html), we could add support to override node shapes as is supported by react-force-graph (https://vasturiano.github.io/react-force-graph/example/custom-node-shape/index-canvas.html)