logger, pow/dagger, pow/ezp: delete dead code

cmd/geth/main.go

cmd/utils/cmd.go

core/block_validator_test.go

core/blockchain.go

errs/errors.go

errs/errors_test.go

logger/example_test.go

logger/log.go

logger/loggers.go

logger/loggers_test.go

logger/logsystem.go

logger/sys.go

logger/types.go

miner/worker.go

node/node_test.go

p2p/server.go

pow/dagger/dagger.go

pow/dagger/dagger_test.go

pow/ezp/pow.go

swarm/network/protocol.go