* internal: replace noarg fmt.Errorf with errors.New
Signed-off-by: jsvisa <delweng@gmail.com>

* tests: replace noarg fmt.Errorf with errors.New
Signed-off-by: jsvisa <delweng@gmail.com>

* tests: go autoimport
Signed-off-by: jsvisa <delweng@gmail.com>

* tests: go autoimport
Signed-off-by: jsvisa <delweng@gmail.com>

---------
Signed-off-by: jsvisa <delweng@gmail.com>

This enables the following linters

- typecheck
- unused
- staticcheck
- bidichk
- durationcheck
- exportloopref
- gosec

WIth a few exceptions.

- We use a deprecated protobuf in trezor. I didn't want to mess with that, since I cannot meaningfully test any changes there.
- The deprecated TypeMux is used in a few places still, so the warning for it is silenced for now.
- Using string type in context.WithValue is apparently wrong, one should use a custom type, to prevent collisions between different places in the hierarchy of callers. That should be fixed at some point, but may require some attention.
- The warnings for using weak random generator are squashed, since we use a lot of random without need for cryptographic guarantees.

This PR adds a new fork which disables EIP-1283. Internally it's called Petersburg,
but the genesis/config field is ConstantinopleFix.

The block numbers are:

    7280000 for Constantinople on Mainnet
    7280000 for ConstantinopleFix on Mainnet
    4939394 for ConstantinopleFix on Ropsten
    9999999 for ConstantinopleFix on Rinkeby (real number decided later)

This PR also defaults to using the same ConstantinopleFix number as whatever
Constantinople is set to. That is, it will default to mainnet behaviour if ConstantinopleFix
is not set.This means that for private networks which have already transitioned
to Constantinople, this PR will break the network unless ConstantinopleFix is
explicitly set!

Tests are now included as a submodule. This should make updating easier
and removes ~60MB of JSON data from the working copy.

State tests are replaced by General State Tests, which run the same test
with multiple fork configurations.

With the new test runner, consensus tests are run as subtests by walking
json files. Many hex issues have been fixed upstream since the last
update and most custom parsing code is replaced by existing JSON hex
types. Tests can now be marked as 'expected failures', ensuring that
fixes for those tests will trigger an update to test configuration. The
new test runner also supports parallel execution and the -short flag.

I forgot to update one instance of "go-ethereum" in commit 3f047be5.

All code outside of cmd/ is licensed as LGPL. The headers
now reflect this by calling the whole work "the go-ethereum library".