0.13.0

Add CapacityError, UrlError, and ProtocolError types to represent the different types of capacity, URL, and protocol errors respectively.
Modify variants Error::Capacity, Error::Url, and Error::Protocol to hold the above errors types instead of string error messages.
Add handshake::derive_accept_key to facilitate external handshakes.
Add support for rustls as TLS backend. The previous tls feature flag is now removed in favor of native-tls and rustls-tls, which allows to pick the TLS backend. The error API surface had to be changed to support the new error types coming from rustls related crates.

0.12.0

Add facilities to allow clients to follow HTTP 3XX redirects.
Allow accepting unmasked clients on the server side to be compatible with some legacy / invalid clients.
Update of dependencies and documentation fixes.