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>

This moves the eth config definition into a separate package, eth/ethconfig. 
Packages eth and les can now import this common package instead of
importing eth from les, reducing dependencies.

Co-authored-by: Felix Lange <fjl@twurst.com>

This commit extends the ethclient test suite and increases code coverage of the ethclient
package from ~15% to >55%. These tests act as early smoke tests to signal issues in the
RPC-interface. E.g. if a functionality like eth_chainId or eth_call breaks, the test
will break.

It didn't actually work because it called a method that doesn't
exist. This fixes it also adds a test.

Co-authored-by: Felix Lange <fjl@twurst.com>

This adds a new client method BlockNumber to fetch the most recent
block number of the chain.

This PR significantly changes the APIs for instantiating Ethereum nodes in
a Go program. The new APIs are not backwards-compatible, but we feel that
this is made up for by the much simpler way of registering services on
node.Node. You can find more information and rationale in the design
document: https://gist.github.com/renaynay/5bec2de19fde66f4d04c535fd24f0775.

There is also a new feature in Node's Go API: it is now possible to
register arbitrary handlers on the user-facing HTTP server. In geth, this
facility is used to enable GraphQL.

There is a single minor change relevant for geth users in this PR: The
GraphQL API is no longer available separately from the JSON-RPC HTTP
server. If you want GraphQL, you need to enable it using the
./geth --http --graphql flag combination.

The --graphql.port and --graphql.addr flags are no longer available.

Fixes #21175

Co-authored-by: sammy007 <sammy007@users.noreply.github.com>
Co-authored-by: Adam Schmideg <adamschmideg@users.noreply.github.com>

EIP-695 was written in 2017. Parity and Infura have support for this
method and we should, too.

TransactionInBlock crashed if json was nil and there was an error
because it tried to access fields `From` and `BlockHash` of the nil object.

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.

ethereum/go-ethereum#16734 introduced BlockHash to the FilterQuery
struct. However, ethclient was not updated to include BlockHash in the actual
RPC request.

The error produced when using a Parity RPC was the following:

ERROR: transaction did not get mined: failed to get tx for txid 0xbdeb094b3278019383c8da148ff1cb5b5dbd61bf8731bc2310ac1b8ed0235226: json: cannot unmarshal non-string into Go struct field txExtraInfo.blockHash of type common.Hash

DialContext allows users to pass a Context object for cancellation.
Close closes the underlying RPC connection.

* core/types: make Signer derive address instead of public key

There are two reasons to do this now: The upcoming ethclient signer
doesn't know the public key, just the address. EIP 208 will introduce a
new signer which derives the 'entry point' address for transactions with
zero signature. The entry point has no public key.

Other changes to the interface ease the path make to moving signature
crypto out of core/types later.

* ethclient, mobile: add TransactionSender

The new method can get the right signer without any crypto, and without
knowledge of the signature scheme that was used when the transaction was
included.

There is currently no simple way to obtain the network ID from a Client. 
This adds a NetworkID method that wraps the net_version JSON-RPC call.

Implements ethereum/EIPs#98

As per #14661 TransactionByHash always returns false for pending.
This uses blockNumber rather than blockHash to ensure that it returns
the correct value for pending and will not suffer side-effects if
eth_getTransactionByHash is fixed in future.

There is no need to depend on the old context package now that the
minimum Go version is 1.7. The move to "context" eliminates our weird
vendoring setup. Some vendored code still uses golang.org/x/net/context
and it is now vendored in the normal way.

This change triggered new vet checks around context.WithTimeout which
didn't fire with golang.org/x/net/context.

This significantly reduces the dependency closure of ethclient, which no
longer depends on core/vm as of this change.

All uses of vm.Logs are replaced by []*types.Log. NewLog is gone too,
the constructor simply returned a literal.

ethclient now returns ethereum.NotFound if the server returns null and
no error while accessing blockchain data.

The light client cannot provide arbitrary transactions. The change to
split transaction access into its own interface emphasizes that
transactions should not be relied on and recommends use of logs.

It should never return null for a known uncle, but even if it does
we can't just crash.

Fixes #3203

ethclient implements the proposed Ethereum Go API. There are no tests at
the moment, a suite that excercises all implementations of the API will
be added later.