* WIP
* Convert Ethcore error to use error_chain
* Use error_chain for ImportError and BlockImportError
* Fix error pattern matches for error_chain in miner
* Implement explicit From for AccountsError
* Fix pattern matches for ErrorKinds
* Handle ethcore error_chain in light client
* Explicitly define Result type to avoid shadowing
* Fix remaining Error pattern matches
* Fix tab space formatting
* Helps if the tests compile
* Fix error chain matching after merge
* WIP
* Replace Rlp with UntrustedRlp in views, explicity unwrap with expect
First pass to get it to compile. Need to figure out whether to do this or to propogate Errors upstream, which would require many more changes to dependent code. If we do this way we are assuming that the views are always used in a context where the rlp is trusted to be valid e.g. when reading from our own DB. So need to fid out whether views are used with data received from an untrusted (e.g. extrernal peer).
* Remove original Rlp impl, rename UntrustedRlp -> Rlp
* Create rlp views with view! macro to record debug info
Views are assumed to be over valid rlp, so if there is a decoding error we record where the view was created in the first place and report it in the expect
* Use $crate in view! macro to avoid import, fix tests
* Expect valid rlp in decode functions for now
* Replace spaces with tabs in new file
* Add doc tests for creating views with macro
* Update rlp docs to reflect removing of UntrustedRlp
* Replace UntrustedRlp usages in private-tx merge
* move common forks and parameters to common params
* port specs over to new format
* fix RPC tests
* parity-machine skeleton
* remove block type
* extract out ethereum-specific methods into EthereumMachine
* beginning to integrate Machine into engines. dealing with stale transitions in Ethash
* initial porting to machine
* move block reward back into engine
* abstract block reward logic
* move last hash and DAO HF logic into machine
* begin making engine function parameters generic
* abstract epoch verifier and ethash block reward logic
* instantiate special ethereummachine for ethash in spec
* optional full verification in verify_block_family
* re-instate tx_filter in a way that works for all engines
* fix warnings
* fix most tests, further generalize engine trait
* uncomment nullengine, get ethcore tests compiling
* fix warnings
* update a bunch of specs
* re-enable engine signer, validator set, and transition handler
* migrate basic_authority engine
* move last hashes into executedblock
* port tendermint
* make all ethcore tests pass
* json-tests compilation
* fix RPC tests: change in gas limit for new block changed PoW hash
* fix minor grumbles
* validate chainspecs
* fix broken import
* fix transaction verification for pre-homestead
* remove old lint silencer
* dispatch requests only to peers with higher TD
* dynamic target for sync rounds
* use round pivots instead of frames, fix test
* fix total difficulty calculation for test client
* fix broken reorg algorithm
* fork test, fix ancestor search
* Allow sync reorg up to pruning history size
* Peer difficulty tracking
* Abort downloading block if received with NewBlock
* Set pruning history to 1200
* Renamed history size field
* move block queue to own module, a couple readability changes
* make block queue generic over verifiable data
also fixes heap size calculation
* make block queue into a more generic verification queue
* some module reoganization
* implement header queue
* clean up verification error messages
