* update tests for istanbul

* tests: updated blockchaintests, see https://github.com/ethereum/tests/issues/637

* tests: update again, hopefully fixed this time

* tests: skip time consuming, run legacy tests

* tests: update again

* build: disable long-running tests on travis

* tests: fix formatting nits

* tests: I hate github's editor

p2p: measure subprotocol bandwidth usage

* vendor: update leveldb

* ethdb/leveldb: disable seek compaction and add metrics

* vendor: udpate latest levledb

* ethdb/leveldb: fix typo

This change adds support for EIP-1898. 

Fixes #18210

This adds an implementation of node discovery via DNS TXT records to the
go-ethereum library. The implementation doesn't match EIP-1459 exactly,
the main difference being that this implementation uses separate merkle
trees for tree links and ENRs. The EIP will be updated to match p2p/dnsdisc.

To maintain DNS trees, cmd/devp2p provides a frontend for the p2p/dnsdisc
library. The new 'dns' subcommands can be used to create, sign and deploy DNS
discovery trees.

dashboard: log dashboard url

* core/state: revert noop finalise, fix copy-commit-copy

* core/state: reintroduce net sstore tracking, extend tests for it

params: remove legacy bootnodes

deepCopy didn't copy pending storage updates, leading to the
creation of blocks with invalid state root.

vendor: pull in USB Windows fixes

params: activate Istanbul on Ropsten, Rinkeby and Görli

params: bump CHTs for the 1.9.4 release

core: fix tx dedup return error count

* les: detailed relative cost metrics

* les: filter txpool relative request statistic

* les: initialize price factors

* les: increased connected bias to lower churn rate

* les: fixed clientPool.setLimits

* core: do not use mutex in GetAncestor

* les: bump factor db version again

* les: add metrics

* les, light: minor fixes

core: dedup known transactions without global lock, track metrics

* txpool: smaller lock portion

* core/tx_pool: fix data race

cmd/evm: make evm default to all ethash protocol changes

This change adds tests for the virtual clock and aligns the interface
with the time package by renaming Cancel to Stop. It also removes the
binary search from Stop because it complicates the code unnecessarily.

core/state: accumulate writes and only update tries when must