Needless dependency on byteorder crate

The dependency on byteorder crate can be easily avoided, since all the relevant functions are already provided by the standard library (including handling endianness).

Example of stdlib replacement for read_ methods can be found here: https://github.com/cbreeden/fxhash/pull/13/files

Writes can be done through to_ne_bytes: https://doc.rust-lang.org/stable/std/primitive.u32.html#method.to_ne_bytes

The change should be quite trivial, but sadly I am under legal restrictions and cannot contribute to this repository.