message: use a slice instead of a string for the `CONST` in paperwallet
diff: @@ -4,14 +4,14 @@ use self::rcw::hmac::Hmac;
  use self::rcw::pbkdf2::{pbkdf2};
  const ITERS : u32 = 10000;
  -const CONST : &str = "IOHK";
  +const CONST : &'static [u8] = b"IOHK";
  fn gen(iv: &[u8], password: &[u8], buf: &mut [u8]) {
  assert!(iv.len() == 4);
  let mut salt = [0u8;8];
  salt[0..4].clone_from_slice(iv);
  - salt[4..8].clone_from_slice(CONST.as_bytes());
  + salt[4..8].clone_from_slice(CONST);
  let mut mac = Hmac::new(Sha512::new(), password);
  pbkdf2(&mut mac, &salt[..], ITERS, buf);
  }
  