* core: lookup txs by block number instead of block hash

Transaction hashes now store a reference to their corresponding
block number as opposed to their hash. In benchmarks this was
shown to reduce storage by over 12 GB.

The main limitation of this approach is that transactions on
non-canonical blocks could never be looked up, however that is
currently not supported.

The database version has been upgraded to version 5 and the
transaction lookup process is backwards-compatible with the
prior two transaction lookup formats prexisting in the
database instance. Tests have been added to ensure this.

* core/rawdb: tiny review nit fixes

 accounts: switch Ledger derivation path to canonical one

* eth/downloader: enable unsync-protection for light client

* eth/downloader: fix tests

* cmd, eth, miner: disable advance sealing if user require

* cmd, console, miner, les, eth: wrap the miner config

* eth: remove todo

* cmd, miner: revert noadvance flag

The reason for this is: if the transaction execution is even longer
than block time, then this kind of transactions is DoS attack.

trie: approximate the wasted cache metaspace closer

eth, les, light: enforce CHT checkpoints on fast-sync too

appveyor.yml: Upgraded to Go 1.12.4

core, eth, les, light: avoid storing computable receipt metadata 

swarm/storage/feed: add context handling/cancellation to Swarm Feeds lookup, fix bad hint lookup bug (#19353)

* swarm/storage/feed/lookup: Add context handling/forwarding

* swarm/storage/feed/lookup: Add test to catch bad hint

* swarm/storage/feed/lookup: Added context cancellation test

 This makes geth fails instead of falling back to local keystore, if the command line flag `--signer` is used

* cmd/clef, signer: make fourbytes its own package, break dep cycle

* signer/fourbyte: pull in a sanitized 4byte database

* swarm/api: fix file descriptor leak in NewTestSwarmServer

Swarm storage (localstore) was not closed. That resulted a
"too many open files" error if `TestClientUploadDownloadRawEncrypted`
was run with `-count 1000`.

* cmd/swarm: speed up StartNewNodes() by parallelization

Reduce cluster startup time from 13s to 7s.

* swarm/api: disable flaky TestClientUploadDownloadRawEncrypted with -race

* swarm/storage: disable flaky TestLDBStoreCollectGarbage (-race)

With race detection turned on the disabled cases often fail with:
"ldbstore_test.go:535: expected surplus chunk 150 to be missing, but got no error"

* cmd/swarm: fix process leak in TestACT and TestSwarmUp

Each test run we start 3 nodes, but we did not terminate them. So
those 3 nodes continued eating up 1.2GB (3.4GB with -race) after test
completion.

6b6c4d1c changed how we start clusters
to speed up tests. The changeset merged together test cases
and introduced a global cluster. But "forgot" about termination.

Let's get rid of "global cluster" so we have a clear owner of
termination (some time sacrifice), while leaving subtests to use the
same cluster.

* clef: bundle 4byte db into clef, fix #19048

* clef: add go-generate directive, remove internal abidb parser tool

* cmd/clef: extend go generate to format asset file

* metrics/prometheus: added prometheus http server and metrics collector

* metrics/prometheus: minor cleanups

* metrics/prometheus: named keys instead name in tag

* metrics/prometheus: minor typo cleanups, sorted report

* clef: update warning-text

* Update cmd/clef/main.go

This reverts commit 5b30aa59.

Update the app download link to the latest version, as requested in #19418

vendor: fix some vendor config leftover

* vendor: remove leftover trace

* Upgrade go-libpcsclite to the latest version

appveyor.yml: Upgraded to Go 1.12.3

* accounts, core, internal, node: Add support for smartcard wallets

* accounts, internal: Changes in response to review

* vendor: pull in missing go-echd library

* accounts/scwallet, console: user friendly card opening

* accounts/scwallet: ordered wallets, tighter events, derivation logs

* accounts, console: frendly card errors, support pin unblock

* accounts/scwallet: fix crypto API change

* accounts/scwallet: rebase and update

* Fix some linter issues

* Remove the direct dependency on libpcsclite

Instead, use a go library that communicates with pcscd over a socket.

Also update the changes introduced by @gravityblast since this PR's
inception

* Temporary fix to the ADBU status call

* fix wallet status update

This is a temporary fix, better checks need to
be performed once the whole process has been
validated.

* Fix key derivation

* Add some documentation

* Update a comment to reflect the workings of the updated system

* Vendor keycard-go/derivationpath

* Formatting fixes

* Add instructions on how to install the card

* Achieve full transaction signature+sending

* PK derivation has to be supported by the card

* Fix linter issues

* Upgrade to keycard app v2.1.1

* Set gballet as codeowner of the smartcard wallet dir

* fix unnecessary condition linter warning

* refuse to overwrite the master key of a previously initialized card

* refresh the account list when initializing the card

* Update the card preparation instructions based on review feedback

* 'sanitize' JSON input

Co-Authored-By: gballet <gballet@gmail.com>

* Apply suggestions from code review

Co-Authored-By: gballet <gballet@gmail.com>

* fix a serialization error

* more review feedback

* More review feedback

* Can now specify the number of empty accounts to derive

* Fix rebase error: include norm package

* Update bip-39 ref and remove ebfe/scard from vendor

* Add missing dependency