Merge remote-tracking branch 'garious/add-as-ref' into develop

src/ed25519.rs

@@ -183,6 +183,12 @@ impl Drop for SecretKey {
     }
 }
 
+impl AsRef<[u8]> for SecretKey {
+    fn as_ref(&self) -> &[u8] {
+        self.as_bytes()
+    }
+}
+
 impl SecretKey {
     /// Expand this `SecretKey` into an `ExpandedSecretKey`.
     pub fn expand<D>(&self) -> ExpandedSecretKey
@@ -715,6 +721,12 @@ impl Debug for PublicKey {
     }
 }
 
+impl AsRef<[u8]> for PublicKey {
+    fn as_ref(&self) -> &[u8] {
+        self.as_bytes()
+    }
+}
+
 impl PublicKey {
     /// Convert this public key to a byte array.
     #[inline]