This reverts commit 4deebaed.

les, les/flowcontrol: implement LES/3

* core: reinit chain from freezer in batches

* core/rawdb: concurrent database reinit from freezer dump

* core/rawdb: reinit from freezer in sequential order

* core, eth: some fixes for freezer

* vendor, core/rawdb, cmd/geth: add db inspector

* core, cmd/utils: check ancient store path forceily

* cmd/geth, common, core/rawdb: a few fixes

* cmd/geth: support windows file rename and fix rename error

* core: support ancient plugin

* core, cmd: streaming file copy

* cmd, consensus, core, tests: keep genesis in leveldb

* core: write txlookup during ancient init

* core: bump database version

* freezer: disable compression on hashes and difficulties

* core/rawdb: address review concerns

* core/rawdb: address review concerns

* 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

* freezer: implement split files for data

* freezer: add tests

* freezer: close old head-file when opening next

* freezer: fix truncation

* freezer: more testing around close/open

* rawdb/freezer: address review concerns

* freezer: fix minor review concerns

* freezer: fix remaining concerns + testcases around truncation

* freezer: docs

* freezer: implement multithreading

* core/rawdb: fix freezer nitpicks + change offsets to uint32

* freezer: preopen files, simplify lock constructs

* freezer: delete files during truncation

* 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

* move error variable to error.go

* Update error.go

Edit "Genesis" to "genesis"

* core: fix import errors on clique crashes + empty blocks

* cosensus/clique, core: add test for the mirrored state issue

* core: address todo question wrt log count

* core: raise a louder warning for non-clique known blocks

* core: import known blocks if they can be inserted as canonical blocks

* core: insert knowns blocks

* core: remove useless

* core: doesn't process head block in reorg function

* core: add tests for canonicality confusion

* core: delete stale future canon number mappings during reorg to shorter+heavier chain

* consensus,core,miner: avoid overhead of creating a new block

* consensus: nitpick dot

* consensus: fix some comment formatting nits

* typo fix

* change to stores

* 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