* build: use golangci-lint

This changes build/ci.go to download and run golangci-lint instead
of gometalinter.

* core/state: fix unnecessary conversion

* p2p/simulations: fix lock copying (found by go vet)

* signer/core: fix unnecessary conversions

* crypto/ecies: remove unused function cmpPublic

* core/rawdb: remove unused function print

* core/state: remove unused function xTestFuzzCutter

* core/vm: disable TestWriteExpectedValues in a different way

* core/forkid: remove unused function checksum

* les: remove unused type proofsData

* cmd/utils: remove unused functions prefixedNames, prefixFor

* crypto/bn256: run goimports

* p2p/nat: fix goimports lint issue

* cmd/clef: avoid using unkeyed struct fields

* les: cancel context in testRequest

* rlp: delete unreachable code

* core: gofmt

* internal/build: simplify DownloadFile for Go 1.11 compatibility

* build: remove go test --short flag

* .travis.yml: disable build cache

* whisper/whisperv6: fix ineffectual assignment in TestWhisperIdentityManagement

* .golangci.yml: enable goconst and ineffassign linters

* build: print message when there are no lint issues

* internal/build: refactor download a bit

* rpc: improve codec abstraction

rpc.ServerCodec is an opaque interface. There was only one way to get a
codec using existing APIs: rpc.NewJSONCodec. This change exports
newCodec (as NewFuncCodec) and NewJSONCodec (as NewCodec). It also makes
all codec methods non-public to avoid showing internals in godoc.

While here, remove codec options in tests because they are not
supported anymore.

* p2p/simulations: use github.com/gorilla/websocket

This package was the last remaining user of golang.org/x/net/websocket.
Migrating to the new library wasn't straightforward because it is no
longer possible to treat WebSocket connections as a net.Conn.

* vendor: delete golang.org/x/net/websocket

* rpc: fix godoc comments and run gofmt

Make it possible to load input from a file. Simlar to `--code` / `--codefile`, have `--input`/`--inputfile`.

This removes the dashboard project. The dashboard was an experimental
browser UI for geth which displayed metrics and chain information in
real time. We are removing it because it has marginal utility and nobody
on the team can maintain it.

Removing the dashboard removes a lot of dependency code and shaves
6 MB off the geth binary size.

golang.org/x/net/websocket is unmaintained, and we have already
switched to using github.com/gorilla/websocket for package rpc.

* accounts/abi/bind, cmd/abigen: implement alias for abigen

* accounts/abi/bind: minor fixes

* accounts/abi/bind: address comments

* cmd/abigen: address comments

* accounts/abi/bind: print error log when identifier collision

* accounts/abi/bind: address comments

* accounts/abi/bind: address comment

This PR implements the LES server RPC API. Methods for server
capacity, client balance and client priority management are provided.

TestEmptyWork* occasionally fails due to timeout. Increase the timeout.

This adds all dashboard changes from the last couple months.
We're about to remove the dashboard, but decided that we should
get all the recent work in first in case anyone wants to pick up this
project later on.

* cmd, dashboard, eth, p2p: send peer info to the dashboard
* dashboard: update npm packages, improve UI, rebase
* dashboard, p2p: remove println, change doc
* cmd, dashboard, eth, p2p: cleanup after review
* dashboard: send current block to the dashboard client

* travis: Enable ARM support

* Include fixes from 20039

* Add a trace to debug the invalid lookup issue

* Try increasing the timeout to see if the arm test passes

* Investigate the resolver issue

* Increase arm64 timeout for clique test

* increase timeout in tests for arm64

* Only test the failing tests

* Review feedback: don't export epsilon

* Remove investigation tricks+include fjl's feeback

* Revert the retry ahead of using the mock resolver

* Fix rebase errors

* les: loose restriction of unit tests

* les: update unit tests

* les, light: slim the unit tests

params: hard-code new CHTs for the 1.9.7 release

* build: bump PPAs to Go 1.13 (via longsleep), keep Trusty on 1.11

* travis, build, vendor: use own Go bundle for PPA builds

* travis, build, internal, vendor: smarter Go bundler, own untar

* build: updated ci-notes with new Go bundling, only make, don't test

* core/evm, contracts: avoid copying memory for input in calls + make ecrecover not modify input buffer

* core/vm: optimize mstore a bit

* core/vm: change Get -> GetCopy in vm memory access

* cmd/puppeth: integrate istanbul into puppeth

* cmd/puppeth: address comment

* cmd/puppeth: use hexutil.Big for fork indicator

* cmd/puppeth: finalize istanbul fork

* cmd/puppeth: fix 2200 for parity, rename is to eip1283ReenableTransition

* cmd/puppeth: fix eip1108

* cmd/puppeth: add blake2f for parity

* cmd/puppeth: add aleth istanbul precompiled

* cmd/puppeth: use hexutil.Big

* cmd/puppeth: fix unit tests

* cmd/puppeth: update testdata

appveyor: bump to Go 1.13.4

* les: rework clientpool

* accounts/abi: fix various issues

The fixed issues include:

(1) If there is no return in a call function, unpack should
return nil error

(2) For some functions which have struct array as parameter,
it will also be detected and generate the struct definition

(3) For event, if it has non-indexed parameter, the parameter
name will also be assigned if empty. Also the internal struct
will be detected and generate struct defition if not exist.

(4) Fix annotation generation in event function

* accounts/abi: add new abi field internalType

* accounts: address comments and add tests

* accounts/abi: replace strings.ReplaceAll with strings.Replace

* params: configure mainnet istanbul block 9069K

* core/forkid: add some more test items for mainnet istanbul

cmd/devp2p, core/forkid: make forkid.Filter API uniform

eth: eth/64 - extend handshake with with fork id

Fix the block import unit test which can time out sometimes.

eth/downloader: fix data race in downloader

* p2p/enode: add Iterator and associated utilities

* p2p/discover: add RandomNodes iterator

* p2p: dial using iterator

* cmd/devp2p: add discv4 crawler

* cmd/devp2p: WIP nodeset filter

* cmd/devp2p: fixup lesFilter

* core/forkid: add NewStaticFilter

* cmd/devp2p: make -eth-network filter actually work

* cmd/devp2p: improve crawl timestamp handling

* cmd/devp2p: fix typo

* p2p/enode: fix comment typos

* p2p/discover: fix comment typos

* p2p/discover: rename lookup.next to 'advance'

* p2p: lower discovery mixer timeout

* p2p/enode: implement dynamic FairMix timeouts

* cmd/devp2p: add ropsten support in -eth-network filter

* cmd/devp2p: tweak crawler log message