* initial impl approval distribution
* initial tests and fixes
* batching seems difficult: different peers have different needs
* bridge: fix test after merge
* some guide updates
* only send assignments to peers who know about the block
* fix a test, add approvals test
* simplify
* do not send assignment to peers for finalized blocks
* guide: protocol input and output
* one more test
* more comments, logs, initial metrics
* fix a typo
* one more thing: early return when reimporting a thing locally