Merge rust-bitcoin#611: Impl Ord and PartialOrd for RecoverableSignature

dbc5465 Impl Ord and PartialOrd for RecoverableSignature (benthecarman)

Pull request description:

ACKs for top commit:
  apoelstra:
    ACK dbc5465 oops, sorry!

Tree-SHA512: decda6b6e7a4929147f5ca00cb2802037c6a297aa816c253e181f1a85ec9e46958469b9d481e2b4aba2c6d86def80bba33a62c507459d82c86cfed4271a23eea

src/ecdsa/recovery.rs

@@ -13,11 +13,11 @@ use crate::ffi::recovery as ffi;
 use crate::{key, Error, Message, Secp256k1, Signing, Verification};
 
 /// A tag used for recovering the public key from a compact signature.
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Debug, Ord, PartialOrd)]
 pub struct RecoveryId(i32);
 
 /// An ECDSA signature with a recovery ID for pubkey recovery.
-#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
+#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash, Ord, PartialOrd)]
 pub struct RecoverableSignature(ffi::RecoverableSignature);
 
 impl RecoveryId {