Merge #579: Followup: Disallow missing Debug implementations for Scalar type.

e597860 Followup: Disallow missing `Debug` implementations for `Scalar` type. (Arik Sosman)

Pull request description:

  Because `Scalar` now implements it, that carveout is no longer necessary.

ACKs for top commit:
  tcharding:
    ACK e597860
  apoelstra:
    ACK e597860

Tree-SHA512: fd9682550cc6bd2d3d59d067d3a0c7faf5767b4c127d86f95c7355ff795189272f399ce2df7d870f85fa3a3d6727fa6debc058171aab965a8f0aa5b5aecff581

Author: apoelstra

src/scalar.rs

@@ -20,7 +20,6 @@ use crate::constants;
 // Internal represenation is big endian to match what `libsecp256k1` uses.
 // Also easier to implement comparison.
 // Debug impl omitted for now, the bytes may be secret
-#[allow(missing_debug_implementations)]
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
 pub struct Scalar([u8; 32]);
 impl_pretty_debug!(Scalar);