Switch to shiny new fast, RLP-less trie (#795)

* Bump codec

* Fix tests

* Patricia trie builds

* Introduce trie

* Some yak shaving.

* Some fixes

* Remove RLP ref

* Fixes

* It builds!

* Some tests fixed

* Another test fix

* Rejig more hashes

* substrate-trie::iterator_works test

* Update lock

* Polish

* Docs

* Undo incorrect "fix" for tests

* Fix nits

substrate/core/trie/src/error.rs

@@ -0,0 +1,29 @@
+// Copyright 2015-2017 Parity Technologies
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::fmt;
+use std::error::Error as StdError;
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+/// Error concerning the Parity-Codec based decoder.
+pub enum Error {
+	/// Bad format.
+	BadFormat,
+}
+
+impl StdError for Error {
+	fn description(&self) -> &str {
+		"codec error"
+	}
+}
+
+impl fmt::Display for Error {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		fmt::Debug::fmt(&self, f)
+	}
+}