Version 0.2.18: A maintainance release

Although functionality is pretty much unchanged, it improves clarity in the documentation and fixes a bug in the tests.

Crates.io: https://crates.io/crates/ffuzzy/0.2.18
Docs.rs: https://docs.rs/ffuzzy/0.2.18/ssdeep/

Full Changelog: v0.2.17...v0.2.18