* begin with a block/state dag approach in prep for fork choice
* add TODOs for fork choice items, add data structure for forks
* remove syncing and processing states for incoming block sync
* simulator only broadcasts blocks now, no more state simulation
* fix sim tests, no more state sim
* bazel rerun
* naive fork choice
* split update head routine
* pesky race conditions
* fork choice rule works
* dag + fork choice working
* canonical head storage across sessions
* todo: save dag
* no more stalling after 10 blocks, using event feeds
* address review
* sync instead uses event feed
* refactored pure funcs into casper package
* tests pass
* fix lint
* refactor get blockhash
* refactor blockhashforslot
* event feed for incoming blocks in chainservice
* use config
* addressed all comments
* fix typo
* address yutaro comment
* using db interface
* check if parent hash in previous slot DAG
* works
* tests
* drop ffg suffix
* bazel gazelle
* full cov validators by height shard
* gazelle
* state tests
* all state tests
* 100% cov types and 99% cover casper
* cov up
* 80% blockchain cov
* fix lint
