* initial fork-choice refactor
* Add fork_choice test for "no votes"
* Initial test with voting: fix handling of unknown validators and parent blocks
* Fix tiebreak of votes
* Cleanup debugging traces
* Complexify the vote test
* fakeHash use the bigEndian repr of number + fix tiebreak for good
* Stash changes: found critical bug in nimcrypto `==` and var openarray
* Passing fork choice tests with varying votes
* Add FFG fork choice scenario + fork choice to the test suite
* Not sure why lmdb / rocksdb reappeared in rebase
* Add sanity checks to .nimble file + integrate fork choice tests to the test DB and test timing
* Cleanup debugging echos
* nimcrypto fix https://github.com/status-im/nim-beacon-chain/pull/864 as been merged, remove TODO comment
* Turn fork choice exception-free
* Cleanup "result" to ensure early return is properly used
* Add a comment on private/public error code vs Result
* result -> results following https://github.com/status-im/nim-beacon-chain/pull/866
* Address comments:
- raises: [Defect] doesn't work -> TODO
- process_attestation cannot fail
- try/except as expression pending Nim v1.2.0
- cleanup TODOs
* re-enable all sanity checks
* tag no raise for process_attestation
* use raises defect everywhere in fork choice and fix process_attestation test
* initial attestation aggregation
* fix usage of committee index, vs index in committee; uniformly set trailing/following distance; document how the only-broadcast-if mechanism works better and what aggregation already happens, not otherwise sufficiently clear; use correct BlockSlot across epoch boundaries
* address inconsistent notion of which slot in past to target for aggregate broadcast; follow 0.11.x aggregate broadcast p2p interface topic
* Fix get_slot_signature(...) call after get_domain(...) change required genesis_validators_root
* mark all spec references which aren't dealt with in other PRs as v0.11.1
* update two more spec refs to v0.11.1
* initial extended validation setup
* flesh out all TODO items for attestation and beaconblock verification
* fix finalization and add chronicles debugging messages
* directly use blockPool.headState rather than pointlessly updating it and document this constraint
* fix logic relating to first-attestation checking; support validating blocks across multiple forks
* initial 0.11.1 spec commit; no test regressions and finalizes in eth2_network_simulation
* with BLS 0.10/0.11 available, stop skipping attester slashing, proposer slashing, and voluntary exist operations fixture tests
* switch param orders to group state.{fork, genesis_validators_root}; bump spec/datatypes spec version for network purposes
* mark attestation construction and broadcast and some minimal/mainnet constants as 0.11.1-compatible; remove phase 1 sharding constants from minimal which don't exist in that preset
* complete (except for get_domain(...)) 0.11.0 beacon chain spec update
* mark compute_start_slot_at_epoch(...), is_active_validator(...), compute_signing_root(...), and get_seed(...) as 0.11.0