* node: expose config in service context
* eth: integrate p2p/dnsdisc
* cmd/geth: add some DNS flags
* eth: remove DNS URLs
* cmd/utils: configure DNS names for testnets
* params: update DNS URLs
* cmd/geth: configure mainnet DNS
* cmd/utils: rename DNS flag and fix flag processing
* cmd/utils: remove debug print
* node: fix test
* eth: chain config (genesis + fork) ENR entry
* core/forkid, eth: protocol independent fork ID, update to CRC32 spec
* core/forkid, eth: make forkid a struct, next uint64, enr struct, RLP
* core/forkid: change forkhash rlp encoding from int to [4]byte
* eth: fixup eth entry a bit and update it every block
* eth: fix lint
* eth: fix crash in ethclient tests