* consensus/ethash, params: implement eip-2384: bump difficulty bomb

* params: EIP 2384 compat checks

* consensus, params: add Muir Glacier block number (mainnet,ropsten) + official name

* core/forkid: forkid tests for muir glacier

* params/config: address review concerns

* params, core/forkid: review nitpicks

* cmd/geth,eth,les: add override option for muir glacier

* params: nit fix