- Add TSNode to get proper coverage on TS files
- Tell Mocha to look for tests in subdirectories
- Configure NYC to look for coverage on all src files
- Move `source-map-support` to being a dev dependency
- Ensure NYC keeps us at 100% code coverage
We were on a really old version of Mocha, and standard practice for JS
code coverage is to use `nyc` now. This switches our code coverage tool
to `nyc`, and gets us on the latest version of Mocha.
Our code coverage did not appear to be working before either,
now it does.
Additionally, Mocha now supports `.mocharc.js` files which let us have
inline comments for configuration. `.mocha.opts` is deprecated, so I
have switched our Mocha configuration to the new format.
If we had configuration that was equal to the default, I have removed it
