Fuzzing

[lwwmanning]

Once the codebase stabilizes more, a couple useful variants of fuzzing:

• rust-fuzz -- good for ensuring that we return Errors instead of panicking (panics should be for programmer error only)
• hypothesis (python) -- great for testing round-tripping of inputs & outputs at the user-facing API

Good example of rust-fuzz usage in croaring-rs: https://github.com/RoaringBitmap/croaring-rs/blob/master/fuzz/Cargo.toml

We can get https://github.com/google/oss-fuzz to continuously run our fuzzing as well.