Refactor/substrate state machine generic (#553)

* Genric over hasher

* WIP start adding NodeCodec

* Add codec to TrieBackend

* Typechecks

* Fix error type

* Cleanup

* Tests build (and fail)

* Fix tests: don't use MemoryDB::default()

* Lockfile

* Address grumbles

* Teach environmental! about generics

* Add Finder artifacts

* whitespace

* Add a toy impl of Hasher and plug it in to Externalities

* Use `uint` and `fixed-hash` from `parity-common`
Remove unused U512
Add test to ensure H256 impls heapsizeof

* lock file updates

* Make hashes Encodable/Decodable

* lock file updates

* Impl FromIterator for TestExternalities so we can collect() and use map!

* Use rustc-hex from crates
Use rlp from master so dependencies do not mess up the scope

* Fix tests in runtime-io

* lockfile shenanigans

* Add a BlakeHasher impl

* Use BlakeHasher in runtime-io

* lockfile updates

* ws

* Add a Blake2/RLP-flavoured NodeCodec

* Use Blake-flavoured Hasher and NodeCodec

* lockfile

* Implement PartialEq and Default for TestExternalities

* Add note about limitations of environmental!

* Make it compile, but this is probably broken

* Derive Debug so tests in executor can work

* Make executor use BlakeHasher

* ws

* WIP make client generic

* typechecks

* cleanup

* client tests pass

* Fix client/db

* cleanup

* Fix network

* Fix rpc

* Fix service

* Make TestExternalities work better au lieu d'un HashMap

* Fix tests in council

* Fix tests in contract

* Fix tests in council

* Fix democracy

* Add comment about odd-looking reexports in tests

* Don't need to load branch

* Fix staking

* Fix session

* Some polkadot fixes and lockfile

* Fix executive

* fixup lockfile

* Fix polkadot/api

* Fix polkadot/service

* Fix polkadot/runtime tests

* Fix tests in test-runtime

* Test fixes

* Fix missing component in the `std` feature

* Use PhantomData and Result from core

* Fix paths
Use core

* load heapsize on wasm

* implement `HeapSizeOf` for wasm

* Add toy impl of `blake2_256` for no_std

* lockfile

* Use kvdb* from parity-common and fix errors

* rebuilt lockfile

* Add dummy impl of `on_advance_round` for rhododendron::Context

* Fix build after merge

* Add HeapSizeOf bound where needed

* Sort out dependencies for no_std

* Add HeapSizeOf bound where needed

* use temp branch pending PR merges

* Remove unneeded tests

* Lock file and wasm artifacts

* lockfile

* Use magic commit for libp2p

* Cleanup

* Implement blake2_256 for no_std

* Back on parity-common master

* missing type params

* Update Cargo.lock

* whitespace

* Rename concrete Rlp node codec "RlpCodec" and use everywhere
Implement a Keccak-flavoured Rlp NodeCodec and use everywhere
Add a KeccakHasher

* Switch to use KeccakHasher

* Lock file and runtimes

* fixup lockfile

* Fix outstanding issue using concrete types (thanks @gnunicorn)

* Cleanup

* More cleanup

* Comment out Blake2 Hasher

* implement ext_keccak256

* Address todo: FetchChecker is generic

* all tests passing