Changes:
* Do not send separate network packets for response codes and msg
len prefixes
* Close streams according to the spec
* Implement more timeouts according to the spec
* Make hello requests during syncing to update our knowledge of
the head block of the other peer.
* Hello is no longer a handshake message
(all handshakes related code was deleted for clarity)
* Deal with the single-parameter inlining defined in the new spec
* add test suite for voluntary exit
* update API to process_voluntary_exit
* Add range check of validator_index for voluntary exits
* Revert to dual single + multiple voluntary exits API + enable in test suite
* no cache or mocking needed
* Add attestation unit test
* process_attestation doesn't throw exceptions
* Allow SSZ deserialization of both real and invalid signatures
* Add new process_attestation checks - pass all process_attestation tests
* Add sanity check for #361
* Fix SSZ testing after fromBytes/fromSSZBytes changes
* Fixed getBeaconBlocks() and getRecentBeaconBlocks() to use BlockPool, not db.
* Got the sync_protocol to compiling state; Removed all obsolete RPC calls
* fix network sim
* mark BeaconState, state list/vector lengths, misc values, get_base_reward(...), verifyStateRoot(...), and process_slot(...) as 0.8.3; update minimal/mainnet config initial values to 0.8.3 by removing GENESIS_FORK_VERSION
* Add sanity check for slot processing (also impacted by https://github.com/status-im/nim-beacon-chain/issues/373)
* use reportDiff also for all state tests vs EF
* initial sanity checks for blocks - workaround zero signature in block headers: https://github.com/status-im/nim-beacon-chain/issues/374
* Remove generic object variant compare commented code
* Add the one block state transition sanity checks
* generalize blocks test to multiple blocks
* simplify slots test runner
* Add official epoch transitions, sanity blocks, sanity slots to the test suite
* Fix index out-of-bounds in initiate_validator_exit - enable proposer slashings unittest
Zahary Karadjov
Dustin Brody
Jacek Sieka
Ștefan Talpalaru
Mamy Ratsimbazafy
Yuriy Glukhov
Eugene Kabanov
Yuriy Glukhov
Bruno Škvorc