Topicprint.js fails when colors aren't loaded from cluster.csv

[Jaimie Murdock]

The process_colors function in topicprint.js needs to be converted into Promise syntax or become a blocking function. Unsure if d3.csv will be a promise in our older d3v3/d3v4 code. It works properly in d3v5, but that's an upgrade I'd like to avoid.

https://datawanderings.com/2018/08/15/d3-js-v5-promise-syntax-examples/