sfhash

This crate contains the SuperFastHash (aka Hsieh Hash) function presented at http://www.azillionmonkeys.com/qed/hash.html

```rust use sfhash::digest;

let hash = digest("Hello World!".asbytes()); asserteq!(hash, 1774740540); ```

The hash value is initialized with the lenght of the input, so the algorithm cannot be used incrementally.