* cmp to reference db if --reference_chaindata provided
* graceful shutdown
* add ./cmd/integration to makefile
* add interruption support for different stages
* don't compare errors directly
```
go run ./cmd/integration reset --chaindata=...
go run ./cmd/integration state_stages -h
go run ./cmd/integration state_stages --chaindata=... --verbosity=3 --block=2_000_000 --unwind=10 --unwind_every=1_000
```
Also, it inherits flags from geth:
```
--pprof.cpuprofile=./cpu.out // to file
--pprof --pprof.port=6060 // launch pprof server
--metrics // sends to prometheus
```
