This PR implements the first one of the "lespay" UDP queries which
is already useful in itself: the capacity query. The server pool is making
use of this query by doing a cheap UDP query to determine whether it is
worth starting the more expensive TCP connection process.

This replaces the github.com/pborman/uuid dependency with
github.com/google/uuid because the former is only a wrapper for
the latter (since v1.0.0).
Co-authored-by: Felix Lange <fjl@twurst.com>

all: define and enable the Berlin hard fork on all networks

This makes the WebSocket message size limit independent of the
limit used for HTTP requests. The new limit for WebSocket messages 
is 15MB.

* les: move serverPool to les/vflux/client

* les: add metrics

* les: moved ValueTracker inside ServerPool

* les: protect against node registration before server pool is started

* les/vflux/client: fixed tests

* les: make peer registration safe

Co-authored-by: Martin Holst Swende <martin@swende.se>

This adds support for EIP-2718 typed transactions as well as EIP-2930
access list transactions (tx type 1). These EIPs are scheduled for the
Berlin fork.

There very few changes to existing APIs in core/types, and several new APIs
to deal with access list transactions. In particular, there are two new
constructor functions for transactions: types.NewTx and types.SignNewTx.
Since the canonical encoding of typed transactions is not RLP-compatible,
Transaction now has new methods for encoding and decoding: MarshalBinary
and UnmarshalBinary.

The existing EIP-155 signer does not support the new transaction types.
All code dealing with transaction signatures should be updated to use the
newer EIP-2930 signer. To make this easier for future updates, we have
added new constructor functions for types.Signer: types.LatestSigner and
types.LatestSignerForChainID. 

This change also adds support for the YoloV3 testnet.
Co-authored-by: Martin Holst Swende <martin@swende.se>
Co-authored-by: Felix Lange <fjl@twurst.com>
Co-authored-by: Ryan Schneider <ryanleeschneider@gmail.com>

Transaction unindexing will be enabled by default as of 1.10, which causes tx status retrieval will be broken without this PR. 

This PR introduces a retry mechanism in TxStatus retrieval.

This PR adds a more CLI flag, so that the les-server can serve light clients even the local node is not synced yet.

This functionality is needed in some testing environments(e.g. hive). After launching the les server, no more blocks will be imported so the node is always marked as "non-synced".

eth/protocols/snap: lower abortion and resumption logs to debug

This removes support for all deprecated flags except --rpc*.

travis: bump builders to Bionic

travis: bump Android NDK version

cmd/utils: disable caching preimages by default

* travis, appveyor, build: bump Go to 1.16

* accounts/abi/bind: fix up Go mod files for Go 1.16

This PR prevents users from submitting transactions without EIP-155 enabled. This behaviour can be overridden by specifying the flag --rpc.allow-unprotected-txs=true. 

This PR introduces:

- db.put to put a value into the database
- db.get to read a value from the database
- db.delete to delete a value from the database
- db.stats to check compaction info from the database
- db.compact to trigger a db compaction

It also moves inspectdb to db.inspect.

* les: refactored server handler

* tests/fuzzers/les: add fuzzer for les server handler

* tests, les: update les fuzzer

tests: update les fuzzer

tests/fuzzer/les: release resources

tests/fuzzer/les: pre-initialize all resources

* les: refactored server handler and fuzzer
Co-authored-by: rjl493456442 <garyrong0905@gmail.com>

* les/lespay/server: fix balance expiration and add test

* les: move client balances to a new db

* les: rename lespayDb to lesDb

In the random sync algorithm used by the DNS node iterator, we first pick a random
tree and then perform one sync action on that tree. This happens in a loop until any
node is found. If no trees contain any nodes, the iterator will enter a hot loop spinning
at 100% CPU.

The fix is complicated. The iterator now checks if a meaningful sync action can
be performed on any tree. If there is nothing to do, it waits for the next root record
recheck time to arrive and then tries again.

Fixes #22306

* eth/protocols/eth: split up the eth protocol handlers

* eth/protocols/eth: define eth-66 protocol messages

* eth/protocols/eth: poc implement getblockheaders on eth/66

* eth/protocols/eth: implement remaining eth-66 handlers

* eth/protocols: define handler map for eth 66

* eth/downloader: use protocol constants from eth package

* eth/protocols/eth: add ETH66 capability

* eth/downloader: tests for eth66

* eth/downloader: fix error in tests

* eth/protocols/eth: use eth66 for outgoing requests

* eth/protocols/eth: remove unused error type

* eth/protocols/eth: define protocol length

* eth/protocols/eth: fix pooled tx over eth66

* protocols/eth/handlers: revert behavioural change which caused tests to fail

* eth/downloader: fix failing test

* eth/protocols/eth: add testcases + fix flaw with header requests

* eth/protocols: change comments

* eth/protocols/eth: review fixes + fixed flaw in RequestOneHeader

* eth/protocols: documentation

* eth/protocols/eth: review concerns about types

io.Reader may return n > 0 and io.EOF at the end of the input stream.
readFull did not handle this correctly, looking only at the error. This fixes
it to check for n == len(buf) as well.

* core/state: copy the snap when copying the state

* core/state: deep-copy snap stuff during state Copy

This PR optimizes the broadcast loop. Instead of iterating twice through a given set of transactions to weed out which peers have and which do not have a tx, to send/announce transactions, we do it only once.