* 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
* make validator set aware of various states
* fix updater build
* clean up contract call
* failing sync test
* adjust tests
* nicer indent [ci skip]
* revert bound divisor
* remove register_account_provider
* build rpc module
* new dummy client
* common EngineSigner struct
* from -> into
* initial report via call
* separate safe from regular contract
* transact_contract
* fix build
* return Signature, docs
* add sign method to some engines
* add safeContract spec
* update specs to new contracts
* use AuthorityRound for contract spec
* add more reporting
* add reporting test
* use gas floor
* shorter
