[ethcore cleanup]: various unrelated fixes from #11493 (#11507)

* [cleanup]: various unrelated fixes from `#11493`

* [revert]: too verbose logging `seal`

* fix nit: don't mix from() and into()

ethcore/engines/basic-authority/src/lib.rs

@@ -75,7 +75,7 @@ fn verify_external(header: &Header, validators: &dyn ValidatorSet) -> Result<(),
 	}
 
 	match validators.contains(header.parent_hash(), &signer) {
-		false => Err(BlockError::InvalidSeal.into()),
+		false => Err(Error::Block(BlockError::InvalidSeal)),
 		true => Ok(())
 	}
 }
@@ -91,7 +91,7 @@ impl BasicAuthority {
 	/// Create a new instance of BasicAuthority engine
 	pub fn new(our_params: BasicAuthorityParams, machine: Machine) -> Self {
 		BasicAuthority {
-			machine: machine,
+			machine,
 			signer: RwLock::new(None),
 			validators: new_validator_set(our_params.validators),
 		}