* Reduce max block timestamp drift to 15 seconds (#7240)
* reduce max block timestamp drift to 15 seconds
* add test for block timestamp validation within allowed drift
* Update kovan HF block number.
* 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
* final engine changes
* migration to v13
* adding and removing pending transitions
* epoch_transition_for
* port snapshot to new engine methods
* final validator set interface
* fix compiler errors
* revert v13/epoch_depth transition
* make call on new epoch
* rolling finality checker
* tests for finality checker
* constructing finality proof upon pending transition
* fix warnings and finality proof checking
* fix compiler warnings in tests
* test fixes
* don't include genesis in finality checking
* change snapshot test chain building logic
* minor refactorings
* fetch epoch transition based on parent, fix divide-by-zero in SimpleList
* fix formatting
* fix ABIs and finality checking in snapshot restoration
* encode signal number in proof
* create more blocks at the end of tests
* update gist to accurate contract code
* test for epoch_transition_for
* fix tests with immediateTransitions parameter
* disable force flag after forcing
* rename ValidatorsChanged to InitiateChange and finalizeSignal to finalizeChange
* a few more validator set tests
* Ethereum Classic Monetary Policy
Create a new parameter `ecip1017EraRounds`. When the block number
passes one era rounds, the reward is reduced by 20%.
See https://github.com/ethereumproject/ECIPs/blob/master/ECIPs/ECIP-1017.md
* Update rewards for uncle miners for ECIP1017
In the monetary policy, the rewards are changed from "up to 7/8 of the
reward" to "1/32 of the reward".
* Fix an off-by-one error in ECIP1017 era calculation
According to
https://github.com/ethereumproject/ECIPs/blob/master/ECIPs/ECIP-1017.md,
when in block number 5,000,000, it should still be in Era 1 (which in
our code `era == 0`). So we need to check whether the `rem` equals to
zero and act accordingly when calculating the era.
* `ecip1017_era_rounds` missing from EthashParams when run in build bot
* strip out ecip1017_eras_block_reward function and add unit test
