std::from_str::FromStr -> std::str::FromStr
Fix String.as_slice() issues
Enum namespaces are now explicit

See
https://github.com/rust-lang/rust/commit/3dcd2157403163789aaf21a9ab3c4d30a7c6494d
Explicit references in function calls

Coercions from [T] to &[T] are no longer implicit (RFC 401)