* 0.7.0 updates which don't change semantics; mostly comment changes
* mark get_attesting_indices, bls_verify, ProposerSlashing, BeaconBlockBody, deposit contract constants, state list length constants, compute_committee, get_crosslink_committee, is_slashable_attestation_data, processAttesterSlashings as 0.7.0; rename BASE_REWARD_QUOTIENT to BASE_REWARD_FACTOR
* complete marking unchanged-in-0.7.0 datatypes as such; a few more have trivial field renamings, etc
* update process_justification_and_finalization to 0.6.2; mark AttesterSlashing as 0.6.2
* replace get_effective_balance(...) with state.validator_registry[idx].effective_balance; rm get_effective_balance, process_ejections, should_update_validator_registry, update_validator_registry, and update_registry_and_shuffling_data; update get_total_balance to 0.6.2; implement process_registry_updates
* rm exit_validator; implement is_slashable_attestation_data; partly update processAttesterSlashings
* mark HistoricalBatch and Eth1Data as 0.6.2; implement get_shard_delta(...); replace 0.5 finish_epoch_update with 0.6 process_final_updates
* mark increase_balance, decrease_balance, get_delayed_activation_exit_epoch, bls_aggregate_pubkeys, bls_verify_multiple, Attestation, Transfer, slot_to_epoch, Crosslink, get_current_epoch, int_to_bytes*, various constants, processEth1Data, processTransfers, and verifyStateRoot as 0.6.2; rm is_double_vote and is_surround_vote
* mark get_bitfield_bit, verify_bitfield, ProposerSlashing, DepositData, VoluntaryExit, PendingAttestation, Fork, integer_squareroot, get_epoch_start_slot, is_active_validator, generate_seed, some constants to 0.6.2; rename MIN_PENALTY_QUOTIENT to MIN_SLASHING_PENALTY_QUOTIENT
* rm get_previous_total_balance, get_current_epoch_boundary_attestations, get_previous_epoch_boundary_attestations, and get_previous_epoch_matching_head_attestations
* update BeaconState to 0.6.2; simplify legacy get_crosslink_committees_at_slot infrastructure a bit by noting that registry_change is always false; reimplment 0.5 get_crosslink_committees_at_slot in terms of 0.6 get_crosslink_committee
* mark process_deposit(...), get_block_root_at_slot(...), get_block_root(...), Deposit, BeaconBlockHeader, BeaconBlockBody, hash(...), get_active_index_root(...), various constants, get_shard_delta(...), get_epoch_start_shard(...), get_crosslink_committee(...), processRandao(...), processVoluntaryExits(...), cacheState(...) as 0.6.2
* rm removed-since-0.5 split(...), is_power_of_2(...), get_shuffling(...); rm 0.5 versions of get_active_validator_indices and get_epoch_committee_count; add a few tests for integer_squareroot
* mark bytes_to_int(...) and advanceState(...) as 0.6.2
* rm 0.5 get_attesting_indices; update get_attesting_balance to 0.6.2
* another tiny commit to poke AppVeyor to maybe not timeout at connecting to GitHub partway through CI: mark get_churn_limit(...), initiate_validator_exit(...), and Validator as 0.6.2
* mark get_attestation_slot(...), AttestationDataAndCustodyBit, and BeaconBlock as 0.6.2
* track justified and head blocks correctly in presence of blank slots
* fix new block state root
* keep list of viable heads instead of walking children
* disable json bitfield deserializer (needs a corresponding serializer)
* fix handshake best & finalized root
* begin 0.6.0: new get_domain/increase_balance/reduce_balance, BeaconState.validator_balances -> BeaconState.balances, some renamed constants, transaction processing changes, SlashableAttestation field name changes, 0.6.0 get_beacon_proposer_index always uses given state's slot, update tests subrepo
* mark get_bitfield_bit/bls_verify_multiple/stat-list-lengths/is_active_validator/is_surround_vote/slot_to_epoch/int_to_bytes/etc as unchanged in 0.6.0; rm Eth1DataVote/maybe_reset_eth1_period and thus adjust expected tree hash test results
* mark verify_bitfield/bls_verify/deposit-contract/VoluntaryExit/PendingAttestation/Historicalbatch/Fork as 0.6.0; update DOMAIN_BEACON_BLOCK to DOMAIN_BEACON_PROPOSER
* update Crosslink to 0.6.0 (also requires tree hashing test result change, so isolate in individual commit)
* mark verify_merkle_branch/get_delayed_activation_exit_epoch/ProposerSlashing/Attestation/AttestationDataAndCustodyBit/hash/integer_squareroot/get_epoch_start_slot/is_double_vote/get_randao_mix/generate_seed as 0.6.0; update reward and penalty quotients; SlashableAttestation -> IndexedAttestation; rm get_fork_version; ATTESTATION_INCLUSION_REWARD_QUOTIENT -> PROPOSER_REWARD_QUOTIENT
* Load full state test + Add json-serialization for Bitfield
* Implement empty_block_transition test (but test is missing the end state)
* Use the provided empty block instead of mocking one
* Add failing block signing test
* Tests that can't be passed now are now "for information" + indent the "information"/hash given
* add simple bitfield type (fixes#19)
* fix bit endianess to match spec
* consolidate attestation and block logging
* cruft cleanup
* run optimizer on tests, speeds up build
