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