tracking incremental state diffs is not feasible like this. because updates are processed after the
trie has been traversed, the iterators' state doesn't fully capture the progress of the diff. since
currently snapshots are the only use case for tracking, let's just support that.
Implements https://github.com/cerc-io/go-ethereum/issues/319
With this we can perform a single pass to process updates.
Also
* refactor code structure around single-pass iteration
* refactor builder metrics to match new set of functions
* fix unit tests by running sequentially
* update ipld-eth-db in compose
* factor out fixture data into external module
* some CI updates
Reviewed-on: #11
* refactor packages, flags, subscriptions
* DRY refactor builder tests
* use mockgen to generate mocks
* update README
* MODE=statediff no longer needed for unit tests
* simplify func names, clean up metrics
* move write params to service field
* sql indexer: confirm quit after ipld cache reset
prevents negative waitgroup panic
* don't let TotalDifficulty become nil
* use forked plugeth, plugeth-utils for now