This change adds support for EIP-1898. 

* 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

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.

Most of these changes are related to the Go 1.13 changes to test binary
flag handling. 

* cmd/geth: make attach tests more reliable

This makes the test wait for the endpoint to come up by polling
it instead of waiting for two seconds.

* tests: fix test binary flags for Go 1.13

Calling flag.Parse during package initialization is prohibited
as of Go 1.13 and causes test failures. Call it in TestMain instead.

* crypto/ecies: remove useless -dump flag in tests

* p2p/simulations: fix test binary flags for Go 1.13

Calling flag.Parse during package initialization is prohibited
as of Go 1.13 and causes test failures. Call it in TestMain instead.

* build: remove workaround for ./... vendor matching

This workaround was necessary for Go 1.8. The Go 1.9 release changed
the expansion rules to exclude vendored packages.

* Makefile: use relative path for GOBIN

This makes the "Run ./build/bin/..." line look nicer.

* les: fix test binary flags for Go 1.13

Calling flag.Parse during package initialization is prohibited
as of Go 1.13 and causes test failures. Call it in TestMain instead.

* les: wait all task routines before drop the peer

* les: address comments

* les: fix issue

les: handler separation

* eth, interal, les: add getHeaderBy* APIs

* internal: address the comment

* eth, internal, les: getHeader nits, missing TD, console callable

This PR adds some hardening in the lower levels of the protocol stack, to bail early on invalid data. Primarily, attacks that this PR protects against are on the "annoyance"-level, which would otherwise write a couple of megabytes of data into the log output, which is a bit resource intensive.

* accounts, cmd, contracts, les: integrate clef for transaction signing

* accounts, cmd/checkpoint-admin, signer/core: minor fixups

* les: remove half-finish APIs

* les: remove half-finish APIs

* all: implement simple checkpoint syncing

cmd, les, node: remove callback mechanism

cmd, node: remove callback definition

les: simplify the registrar

les: expose checkpoint rpc services in the light client

les, light: don't store untrusted receipt

cmd, contracts, les: discard stale checkpoint

cmd, contracts/registrar: loose restriction of registeration

cmd, contracts: add replay-protection

all: off-chain multi-signature contract

params: deploy checkpoint contract for rinkeby

cmd/registrar: add raw signing mode for registrar

cmd/registrar, contracts/registrar, les: fixed messages

* cmd/registrar, contracts/registrar: fix lints

* accounts/abi/bind, les: address comments

* cmd, contracts, les, light, params: minor checkpoint sync cleanups

* cmd, eth, les, light: move checkpoint config to config file

* cmd, eth, les, params: address comments

* eth, les, params: address comments

* cmd: polish up the checkpoint admin CLI

* cmd, contracts, params: deploy new version contract

* cmd/checkpoint-admin: add another flag for clef mode signing

* cmd, contracts, les: rename and regen checkpoint oracle with abigen

* les: reject client connection if it makes too much invalid req

* les: address comments

* les: use uint32

* les: fix variable name

* les: add invalid counter for duplicate invalid req

* eth, les: reject stale request

* les: reuse local head number

* p2p/enr: add entries for for IPv4/IPv6 separation

This adds entry types for "ip6", "udp6", "tcp6" keys. The IP type stays
around because removing it would break a lot of code and force everyone
to care about the distinction.

* p2p/enode: track IPv4 and IPv6 address separately

LocalNode predicts the local node's UDP endpoint and updates the record.
This change makes it predict IPv4 and IPv6 endpoints separately since
they can now be in the record at the same time.

* p2p/enode: implement base64 text format
* all: switch to enode.Parse(...)

This allows passing base64-encoded node records to all the places that
previously accepted enode:// URLs. The URL format is still supported.

* cmd/bootnode, p2p: log node URL instead of ENR

...and return the base64 record in NodeInfo.

les, les/flowcontrol: implement LES/3

* eth, les: reject light client connection is server is not synced

* eth, les: rename function and variables

* les: format

* les: avoid fetcher deadlock on requestChn

* all: freezer style syncing

core, eth, les, light: clean up freezer relative APIs

core, eth, les, trie, ethdb, light: clean a bit

core, eth, les, light: add unit tests

core, light: rewrite setHead function

core, eth: fix downloader unit tests

core: add receipt chain insertion test

core: use constant instead of hardcoding table name

core: fix rollback

core: fix setHead

core/rawdb: remove canonical block first and then iterate side chain

core/rawdb, ethdb: add hasAncient interface

eth/downloader: calculate ancient limit via cht first

core, eth, ethdb: lots of fixes

* eth/downloader: print ancient disable log only for fast sync

* core, eth, trie: bloom filter for trie node dedup during fast sync

* eth/downloader, trie: address review comments

* core, ethdb, trie: restart fast-sync bloom construction now and again

* eth/downloader: initialize fast sync bloom on startup

* eth: reenable eth/62 until we properly remove it

* les, light: implement ODR transaction lookup by hash

* les: delete useless file

* internal/ethapi: always use backend to find transaction

* les, eth, internal/ethapi: renamed GetCanonicalTransaction to GetTransaction

* light: add canonical header verification to GetTransaction

This change makes getBalance, getCode, getStorageAt, getProof,
call, getTransactionCount return an error if the block number in
the request doesn't exist. getHeaderByNumber still returns null
for missing headers.