Major update to work with v3 of the Trove API. Other changes include:
- Each harvest is now documented by two automatically-generated files. The `ro-crate-metadata.json` contains contextual information about the harvest, such as the date, harvester version etc, saved in [RO-Crate](https://www.researchobject.org/ro-crate/) format. The second `harvester_config.json` saves the query parameters sent to the Trove API and the harvester options. This means you always know how and when a harvest was created, and can share information about the provenance of a harvested dataset in a standard way.
- You can now initiate a harvest by pointing to an existing `harvester_config.json` file. This makes it easy to rerun a harvest at some future date in order to pick up changes in the Trove corpus.
- The way `results.csv` files are generated has been changed to make it a bit more memory friendly (no longer loading the whole ndjson file into Pandas).