* p2p/simulation: WIP minimal snapshot test

* p2p/simulation: Add snapshot create, load and verify to snapshot test

* build: add test tag for tests

* p2p/simulations, build: Revert travis change, build test sym always

* p2p/simulations: Add comments, timeout check on additional events

* p2p/simulation: Add benchmark template for minimal peer protocol init

* p2p/simulations: Remove unused code

* p2p/simulation: Correct timer reset

* p2p/simulations: Put snapshot check events in buffer and call blocking

* p2p/simulations: TestSnapshot fail if Load function returns early

* p2p/simulations: TestSnapshot wait for all connections before returning

* p2p/simulation: Revert to before wait for snap load (5e75594)

* p2p/simulations: add "conns after load" subtest to TestSnapshot

and nudge

* core: sanitize more TxPoolConfig fields

* core: fix TestTransactionPendingMinimumAllowance

* downloader: fix edgecase where returned index is OOB for downloader

* downloader: documentation
Co-Authored-By: Nholiman <martin@swende.se>

* swarm/network/stream: fix visualized_snapshot_sync_sim_test

* swarm/network/stream: updated visualized snapshot-test;data in p2p event

* swarm/network/stream: cleanup visualized snapshot sync test

* swarm/network/stream: re-enable t.Skip for visualized test

* swarm/network/stream: addressed PR comments

* fix slice unpack bug in accounts/abi

argument type and name were reversed

* usbwallet: check returned error when decoding hexstr

* Update accounts/usbwallet/ledger.go
Co-Authored-By: CoreyLin <514971757@qq.com>

* usbwallet: check hex decode error

* swarm/shed: add metrics to each shed db

* swarm/shed: push metrics prefix up

* swarm/shed: rename prefix to metricsPrefix

* swarm/shed: unexport Meter, remove Mutex for quit channel

* geth/core/eth: implement constantinople override flag

* les: implemnent constantinople override flag for les clients

* cmd/geth, eth, les: fix typo, move flag to experimentals

cmd/faucet, cmd/puppeth: fix enode and compose regressions, expose UDP

cmd/swarm, metrics, swarm/api/client, swarm/storage, swarm/metrics, swarm/api/http: add instrumentation (#18274)

params: update CHTs for the 1.8.20 release

cmd, eth: add support for `--whitelist <blocknum>=<hash>`

* Rejects peers that respond with a different hash for any of the passed in block numbers.
* Meant for emergency situations when the network forks unexpectedly.

* Fix typo in interfaces.go

* Update interfaces.go

light: fix duplicated argument in bytes.Equal call

Most probably a copy/paste kind of error.
Found with gocritic `dupArg` checker.

node,rpc: remove unused log in ipc listener function

core/vm, eth: add standard json tracing into filesystem dumps