Fix wrong field names
Fix `build_attestation_data` and other PR feedback from Danny and
Terence
1. Rename `get_previous_slot` to `compute_previous_slot`
2. Break down `build_empty_block` into
`get_state_and_beacon_parent_root_at_slot`, use it in
`build_shard_block`
3. Set defult `slot` to `shard_state.slot + 1` in `build_shard_block`
Update `verify_shard_block_message`: check beacon_parent_root at fork
choice rule stage instead of state transition
Fix `beacon-chain.md`
1. Fix typo `attestation.slot == state.slot` -> `attestation.data.slot == state.slot` in `is_winning_attestation`
2. Check `verify_shard_transition_false_positives` **after** `process_operations`
3. Fix `shard_attestations` filter in `process_crosslinks`: since attestations come from block, should use `attestation.data.slot + MIN_ATTESTATION_INCLUSION_DELAY == state.slot`
4. [TBD] Allow empty `light_client_signature` to make the tests pass
5. [TBD] Add `is_shard_attestation`, filter out empty `ShardTransition()`
Rework `test_process_crosslink`
Add basic phase 1 `test_blocks`
Add more test cases
Revert `is_shard_attestation` and fix test cases backward compatibility.
Remove `test_process_beacon_block_no_shard_transition` and consider it as invalid case.
Use `ShardBlock` in `shard_state_transition`
PR feedback
1. Rename `ShardState.data` -> `ShardState.transition_digest`
2. Rename `compute_shard_transition_data` to `compute_shard_transition_digest`
3. Add `assert state.slot > PHASE_1_GENESIS_SLOT` just in case, may move it later
Add `get_post_shard_state` as a pure function wrapper
PR feedback from Danny and some refactor
1. Add stub `PHASE_1_GENESIS_SLOT`
2. Rename `get_updated_gasprice` to `compute_updated_gasprice`
3. Rename `compute_shard_data_roots` to `compute_shard_body_roots`
Apply shard transition for the skipped slots
Refactor `shard_state_transition`
Get `beacon_parent_root` from offset slot
Add more test
Add `verify_shard_block_message`
Add `> 0`
Keep `beacon_parent_block` unchanged in `is_valid_fraud_proof`
Remove some lines
Fix type
Refactor + simplify skipped slot processing
There's room for ambiguity as to what `count` means - this clarifies
that it always relates to the slot, and not the number of blocks in the
response which allows clients to request ranges epoch by epoch (for
example) without worrying about overlaps caused by empty slots.
