* eth: update higest block we know during the sync if a higher was found

* eth: avoid useless sync in fast sync

Fixes #3326, #14472

* go-metrics: fork library and introduce ResettingTimer and InfluxDB reporter.

* vendor: change nonsense/go-metrics to ethersphere/go-metrics

* go-metrics: add tests. move ResettingTimer logic from reporter to type.

* all, metrics: pull in metrics package in go-ethereum

* metrics/test: make sure metrics are enabled for tests

* metrics: apply gosimple rules

* metrics/exp, internal/debug: init expvar endpoint when starting pprof server

* internal/debug: tiny comment formatting fix

This commit reduces database I/O by not writing every state trie to disk.

* les: limit number of LES connections

* eth, cmd/utils: light vs max peer configuration logic

The first should address a long term issue where we recommend a gas
price that is greater than that required for 50% of transactions in
recent blocks, which can lead to gas price inflation as people take
this figure and add a margin to it, resulting in a positive feedback
loop.

Fixes #15777 because null is now allowed for hexutil.Bytes.

* core/types, core/vm, eth, tests: regenerate gencodec files

* Makefile: update devtools target

Install protoc-gen-go and print reminders about npm, solc and protoc.
Also switch to github.com/kevinburke/go-bindata because it's more
maintained.

* contracts/ens: update contracts and regenerate with solidity v0.4.19

The newer upstream version of the FIFSRegistrar contract doesn't set the
resolver anymore. The resolver is now deployed separately.

* contracts/release: regenerate with solidity v0.4.19

* contracts/chequebook: fix fallback and regenerate with solidity v0.4.19

The contract didn't have a fallback function, payments would be rejected
when compiled with newer solidity. References to 'mortal' and 'owned'
use the local file system so we can compile without network access.

* p2p/discv5: regenerate with recent stringer

* cmd/faucet: regenerate

* dashboard: regenerate

* eth/tracers: regenerate

* internal/jsre/deps: regenerate

* dashboard: avoid sed -i because it's not portable

* accounts/usbwallet/internal/trezor: fix go generate warnings

This reverts commits 85a1eda5 (#15792) and c495bca4 (#15787)
because they introduce database writes during tracing.

* eth: uncaptialize tracer preimage error message

* eth: improve very important error message

* accounts, consensus, core, eth: make chain maker consensus agnostic

* consensus, core: move CalcDifficulty to Engine interface

* consensus: add docs for calcDifficulty function

* consensus, core: minor comment fixups

* cmd, core, eth/tracers: support fancier js tracing

* eth, internal/web3ext: rework trace API, concurrency, chain tracing

* eth/tracers: add three more JavaScript tracers

* eth/tracers, vendor: swap ottovm to duktape for tracing

* core, eth, internal: finalize call tracer and needed extras

* eth, tests: prestate tracer, call test suite, rewinding

* vendor: fix windows builds for tracer js engine

* vendor: temporary duktape fix

* eth/tracers: fix up 4byte and evmdis tracer

* vendor: pull in latest duktape with my upstream fixes

* eth: fix some review comments

* eth: rename rewind to reexec to make it more obvious

* core/vm: terminate tracing using defers

Fixes #15196

Updated use of Parallel and added some subtests to help isolate
them. Increased timeout in RequestHeadersByNumber so it
doesn't time out and causes other tests to break.

* cmd, consensus, eth: split ethash related config to it own

* eth, consensus: minor polish

* eth, consenus, console: compress pow testing config field to single one

* consensus, eth: document pow mode

* console: fix typo in comment

* contracts/release: fix typo in comment

* core: fix typo in comment

* eth: fix typo in comment

* miner: fix typo in comment

* eth, internal: Implement  using trie diffs

* eth, internal: Changes in response to review

* eth: More fixes to getModifiedAccountsBy*

* eth: minor polishes on error capitalization

it's -> its

pet peeve, and I like to imagine I'm not alone.

* build: enable unconvert linter

 - fixes #15453
 - update code base for failing cases

* cmd/puppeth: replace syscall.Stdin with os.Stdin.Fd() for unconvert linter

* core, eth, les: fix messy code

* les: fixed tx status test and rlp encoding

* core: add a workaround for light sync