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

* core/asm: Fix encoding of pushed labels

EVM uses big-endian byte-order, so to pad a label value to 4 bytes,
zeros must be added to the front, not the end.

* core/asm: Fix PC calculations when a label is pushed

Incrementing PC by 5 is only correct if the label appears after a jump,
in which case there is an implicit push. When it appears after an explicit
push, PC should only be incremented by 4.

* core/asm: Allow JUMP with no argument

This way, a label can be pushed explicitly, or loaded from memory to
implement a jump table.

When we flush a batch of trie nodes into database during the state
sync, we should guarantee that all children should be flushed before
parent.

Actually the trie nodes commit order is strict by: children -> parent.
But when we flush all ready nodes into db, we don't need the order
anymore since

    (1) they are all ready nodes (no more dependency)
    (2) underlying database provides write atomicity

This way, the output of `evm compile` can be used directly in `evm
--codefile code.txt run`, without stripping the trailing newline first.

The gas price was not passed to the `EstimateGas` function. As a result,
conditional execution paths depending on `tx.gasprice` could be not
correctly processed and we could get invalid gas estimates for contract
function calls.

This PR adds a new unit test in miner package which will create some blocks from miner and then import into another chain. In this way, we can ensure all blocks generated by Geth miner obey consensus rules.

Changed http:// to https:// on links in dashboard/README.md

docs: change http to https on links in log/README.md