Delinting, deadcode removal and vetting

There's a lot of changes here, but it was worth it.

Please confirm that I have made the correct change [here](https://github.com/kortschak/cayley/commit/bf6412b55db2b8db4a1d1f9126fc5d126bfc0aa9#diff-eda8d0af857fd67feb16a3b002bb3144L157).