tweetnacly 0.2.0

Bindings for TweetNaCl, with a couple of additions: flexible SHA2-512 hash, detached mode.
Documentation
fn main() {
    #[cfg(feature = "fast")]
    cc::Build::new()
        .warnings(true)
        .extra_warnings(true)
        .opt_level(3)
        .define("OMIT_POLY1305", None)
        .file("tweetnacl.c")
        .compile("tweetnacl"); // outputs `libtweetnacl.a`
    #[cfg(not(feature = "fast"))]
    cc::Build::new()
        .warnings(true)
        .extra_warnings(true)
        .opt_level(3)
        .file("tweetnacl.c")
        .compile("tweetnacl"); // outputs `libtweetnacl.a`
    println!("cargo:rerun-if-changed=tweetnacl.c");
    println!("cargo:rerun-if-env-changed=CARGO_FEATURE_fast");
}