1. Updates or replaces outdated dependencies (eg, replacing a version of the Prysm client with the latest zrnt).
2. Add support for parsing Bellatrix-era BeaconState and BeaconBlocks
3. Adds flags for toggling the processing of BeaconBlocks and BeaconState. This is particularly important because processing and storing the BeaconState at this time would be too expensive to really do (see: Temporarily disable BeaconState indexing #75 and [Feature] Reduce the Amount of DB Space the Beacon Chain Needs #71)
4. Fixes flaky event handling. The previous code would not reconnect in the case of errors with the SSE connection. This enables automatic reconnection in the case of error (default in the updated v2 SSE library dependency), and also adds a timeout so that if no event is received in 2.5x the block time, the SSE connection is closed and re-established.
5. Other refactoring and cleanup (eg, changing the type of slot from int to Slot (uint64)).
Thomas E Lackey
27fa54c6dc