Add rhine-cassava

[turion]

• [ ] Clean up git history
• [x] Add a few more CSV tests
• [ ] Add a few file unit tests
• [ ] Use in a bigger example
• [ ] Add CSV writing tools
• [ ] Timestamping from CSVs, where one can maybe specify the timestamp column

[turion]

Consider adding a Frames clock as well (or instead): https://hackage.haskell.org/package/Frames

[turion]

I've observed runtime errors with this approach in the wild. Possibly, the way I'm reading the file here isn't that good, and instead I should use the streaming interface https://hackage.haskell.org/package/cassava-0.5.3.0/docs/Data-Csv-Streaming.html#g:2 But this would mean not reusing the file clock. Which is fine.

[turion]

I've observed runtime errors with this approach in the wild.

I definitely need hardened tests that would have detected these errors.