Fix a few typos and unused warnings.

ethcore/src/lib.rs

@@ -76,9 +76,7 @@ extern crate journaldb;
 extern crate keccak_hash as hash;
 extern crate keccak_hasher;
 extern crate kvdb;
-// Note: in `ethcore` this is only used by tests, so without `#[cfg(test)]` there's a warning.
-// However, when building `parity-ethereum` this is needed. So there's something funny going on
-// here.
+#[cfg(any(test, feature = "test-helpers"))]
 extern crate kvdb_memorydb;
 
 extern crate len_caching_lock;
@@ -97,7 +95,6 @@ extern crate rand;
 extern crate rayon;
 extern crate rlp;
 extern crate parity_util_mem;
-extern crate parity_util_mem as mem;
 extern crate parity_util_mem as malloc_size_of;
 extern crate rustc_hex;
 extern crate serde;

ethcore/src/trace/types/trace.rs

@@ -51,7 +51,7 @@ impl CreateResult {
 	}
 }
 
-/// Description of a _call_ action, either a `CALL` operation or a message transction.
+/// Description of a _call_ action, either a `CALL` operation or a message transaction.
 #[derive(Debug, Clone, PartialEq, RlpEncodable, RlpDecodable)]
 pub struct Call {
 	/// The sending account.
@@ -102,7 +102,7 @@ impl Call {
 	}
 }
 
-/// Description of a _create_ action, either a `CREATE` operation or a create transction.
+/// Description of a _create_ action, either a `CREATE` operation or a create transaction.
 #[derive(Debug, Clone, PartialEq, RlpEncodable, RlpDecodable)]
 pub struct Create {
 	/// The address of the creator.

ethcore/types/src/transaction/error.rs

@@ -116,7 +116,7 @@ impl fmt::Display for Error {
 			CodeBanned => "Contract code is temporarily banned.".into(),
 			InvalidChainId => "Transaction of this chain ID is not allowed on this chain.".into(),
 			InvalidSignature(ref err) => format!("Transaction has invalid signature: {}.", err),
-			NotAllowed => "Sender does not have permissions to execute this type of transction".into(),
+			NotAllowed => "Sender does not have permissions to execute this type of transaction".into(),
 			TooBig => "Transaction too big".into(),
 			InvalidRlp(ref err) => format!("Transaction has invalid RLP structure: {}.", err),
 		};