* separate migration from util and make its dependencies into libs:
* snappy
* kvdb
* error
* common
* renamed common -> macros
* util error does not depend on snappy module
* ethsync does not depend on util nor ethcore_error
* nibbleslice and nibblevec merged with patricia_trie crate
* removed unused dependencies from util
* util journaldb traits does not need to be public
* util_error
* fixed ethcore compile error
* ignore .swo files
* Update chain.rs
* 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
