* core: only fire one chain head per batch

* miner: announce chan events synchronously

* ethdb: add Putter interface and Has method

* ethdb: improve docs and add IdealBatchSize

* ethdb: remove memory batch lock

Batches are not safe for concurrent use.

* core: use ethdb.Putter for Write* functions

This covers the easy cases.

* core/state: simplify StateSync

* trie: optimize local node check

* ethdb: add ValueSize to Batch

* core: optimize HasHeader check

This avoids one random database read get the block number. For many uses
of HasHeader, the expectation is that it's actually there. Using Has
avoids a load + decode of the value.

* core: write fast sync block data in batches

Collect writes into batches up to the ideal size instead of issuing many
small, concurrent writes.

* eth/downloader: commit larger state batches

Collect nodes into a batch up to the ideal size instead of committing
whenever a node is received.

* core: optimize HasBlock check

This avoids a random database read to get the number.

* core: use numberCache in HasHeader

numberCache has higher capacity, increasing the odds of finding the
header without a database lookup.

* core: write imported block data using a batch

Restore batch writes of state and add blocks, tx entries, receipts to
the same batch. The change also simplifies the miner.

This commit also removes posting of logs when a forked block is imported.

* core: fix DB write error handling

* ethdb: use RLock for Has

* core: fix HasBlock comment

Fixes #15004

- dao.go is already present in consensus/misc
- core/dao.go is not used anywhere in the codebase

eth: disable fast sync after pivot is committed

core/bloombits, eth/filter: transformed bloom bitmap based log search

core: use blocks and avoid deep reorgs in txpool

eth: use maxpeers from p2p layer instead of extra config

Dockerfile, cmd/puppeth: fix missing SSL certificates, use main image in puppeth

core: make txpool operate on immutable state

bmt is a new package that provides hashers for binary merkle tree hashes on
size-limited chunks. the main motivation is that using BMT hash as the chunk
hash of the swarm hash offers logsize inclusion proofs for arbitrary files on a
32-byte resolution completely viable to use in challenges on the blockchain.

Dockerfile: multi-stage builds, Go 1.9

* cmd/evm: adds ability to run individual state test file

* cmd/evm: Fix statetest runner to be more json friendly

* cmd/evm, tests: minor polishes, dump state on fail

* core/vm: Make max_codesize only applicable post Spurious Dragon/158/155/161/170

* tests: Remove expected failure

* core: Fix flaw where underpriced locals were removed

* core: minor code cleanups for tx pool tests

Using a Timer over Ticker seems to be a lot better, though I cannot fully
account for why that it behaves so (since Ticker should be more bursty, but not
necessarily more active over time, but that may depend on how long window it
uses to decide on when to tick next)

core/vm: more benchmarks