* add helper for beacon committee length (used for quickly validating
attestations)
* refactor some attestation checks to do cheap checks early
* validate attestation epoch before computing active validator set
* clean up documentation / comments
* fill state cache on demand
* avoid converting from uint64 to int, and where most feasible, int type conversion at all
* .len.uint64 -> .len64
* fix 32-bit compilation
* try keeping state_sim loop variable/bounds as int for 32-bit Azure
* len64 -> lenu64
* cache beacon committee size calculation
this fixes a bug in get_validator_churn_limit as well
* fix
* make committee counts consistently uint64
mixing feels like the worst of the two worlds
* Initial implementation of runtime bls skipping.
Add libnfuzz skipBLSValidation handling, check that it propagates.
* Rename skipBLSValidation -> skipBlsValidation, start skipStateRootValidation
* Replace skipValidation flags with more granular flags.
Also added skipBlockParentRootValidation flag
Mainly replaced with skipBlsValidation but also StateRoot or
BlockParentRootValidation flags where appropriate.
* Adjust interop test to pass when skipping merkle validation.
* Stop skipping validation for mainchain_monitor.
* Remove comment.
* Also skipMerkleValidation for test_beacon_chain_db.
* beacon node code cleanup
* rudimentary error checking on mainnet monitor
* start client even when sending deposit
* work around missing block number exception
* connect to testnet with web3 url
* pretty-print digests in json
* Move BeaconNode type to its own file (fewer imports)
* disentangle sync protocol/request manager
* fix some old nimisms
* de-fear some logs
* simplify eth1 data production
* add stack tracing to release builds
* drop release compile flag for testnet
* spec updates
* make several constants uint64 to help minimize casting
* document data type woes - will have to revisit these
* change comment style on fields and constants to make room for better
comments
* add BLSVerify and BLSAddPbkeys facades to insulate spec code from
milagro
* fix proof of possession type
* drop explicitly ordered container fields from ssz - there's an issue
open to sort this out before committing it to the spec