Update rust edition to 2021 (#749)

* build: update rust edition 2021

* cargo: format all

* build: fix tests and warnings

libwallet/Cargo.toml

@@ -8,7 +8,7 @@ repository = "https://github.com/mimblewimble/grin-wallet"
 keywords = [ "crypto", "grin", "mimblewimble" ]
 exclude = ["**/*.grin", "**/*.grin2"]
 #build = "src/build/build.rs"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 blake2-rfc = "0.2"

libwallet/src/mwixnet/onion/crypto/dalek.rs

@@ -117,11 +117,13 @@ impl Writeable for DalekPublicKey {
 }
 
 /// Encapsulates an ed25519_dalek::Signature and provides (de-)serialization
+#[allow(dead_code)]
 #[derive(Clone, Debug, PartialEq)]
 pub struct DalekSignature(Signature);
 
 impl DalekSignature {
 	/// Convert hex string to DalekSignature.
+	#[allow(dead_code)]
 	pub fn from_hex(hex: &str) -> Result<Self, DalekError> {
 		let bytes = grin_util::from_hex(hex)
 			.map_err(|_| DalekError::HexError(format!("failed to decode {}", hex)))?;
@@ -131,6 +133,7 @@ impl DalekSignature {
 	}
 
 	/// Verifies DalekSignature
+	#[allow(dead_code)]
 	pub fn verify(&self, pk: &DalekPublicKey, msg: &[u8]) -> Result<(), DalekError> {
 		pk.as_ref()
 			.verify(&msg, &self.0)