The policy is that the minimum Rust version required to use this crate can be increased in minor version updates. For example, if Fasyslog 1.0 requires Rust 1.20.0, then Fasyslog 1.0.z for all values of z will also require Rust 1.20.0 or newer. However, Fasyslog 1.y for y > 0 may require a newer minimum version of Rust.
I'm fine with the current API design and ready for a 1.0 release. Just leave a few months for feedback on the crate's usability. If you have any suggestions or feedback, please open an issue.