Use secp256k1 qualified path instead of underscore

We can use the qualified path for create type aliases, this is arguably
easier to read and reduces the number of LOC.

Author: tcharding

src/util/schnorr.rs

@@ -20,20 +20,18 @@
 use core::fmt;
 use prelude::*;
 
-use secp256k1::{XOnlyPublicKey as _XOnlyPublicKey, KeyPair as _KeyPair};
-
 use secp256k1::{self, Secp256k1, Verification, constants};
 use hashes::Hash;
 use util::taproot::{TapBranchHash, TapTweakHash};
 use SchnorrSighashType;
 
 /// Deprecated re-export of [`secp256k1::XOnlyPublicKey`]
 #[deprecated(since = "0.28.0", note = "Please use `util::key::XOnlyPublicKey` instead")]
-pub type XOnlyPublicKey = _XOnlyPublicKey;
+pub type XOnlyPublicKey = secp256k1::XOnlyPublicKey;
 
 /// Deprecated re-export of [`secp256k1::KeyPair`]
 #[deprecated(since = "0.28.0", note = "Please use `util::key::KeyPair` instead")]
-pub type KeyPair = _KeyPair;
+pub type KeyPair = secp256k1::KeyPair;
 
 /// Untweaked BIP-340 X-coord-only public key
 pub type UntweakedPublicKey = ::XOnlyPublicKey;