Make member functions of U256?

[recmo]

On 2019-07-09 @recmo wrote in f108f29 “Factor U256 into own crate”:

Make member functions of U256?

// TODO: This seems out of scope for U256 to export.
pub mod utils;

pub use crate::u256::U256;

// TODO: Make member functions of U256?
pub use gcd::{gcd, gcd_extended};
#[cfg(not(feature = "std"))]
extern crate no_std_compat as std;

From algebra/u256/src/lib.rs:50