Fixes #15777 because null is now allowed for hexutil.Bytes.

* core/types, core/vm, eth, tests: regenerate gencodec files

* Makefile: update devtools target

Install protoc-gen-go and print reminders about npm, solc and protoc.
Also switch to github.com/kevinburke/go-bindata because it's more
maintained.

* contracts/ens: update contracts and regenerate with solidity v0.4.19

The newer upstream version of the FIFSRegistrar contract doesn't set the
resolver anymore. The resolver is now deployed separately.

* contracts/release: regenerate with solidity v0.4.19

* contracts/chequebook: fix fallback and regenerate with solidity v0.4.19

The contract didn't have a fallback function, payments would be rejected
when compiled with newer solidity. References to 'mortal' and 'owned'
use the local file system so we can compile without network access.

* p2p/discv5: regenerate with recent stringer

* cmd/faucet: regenerate

* dashboard: regenerate

* eth/tracers: regenerate

* internal/jsre/deps: regenerate

* dashboard: avoid sed -i because it's not portable

* accounts/usbwallet/internal/trezor: fix go generate warnings

* go-ethereum/dashboard: update assets.go

Use current rsc/go-bindata instead of jteeuwen/go-bindata, to get
balanced tree in very long string concatenations.
This works around problems in current Go distributions.

For golang/go#23222.

* dashboard: run last two go:generate steps for linter

Also raise traceLimit once again and print the VM
error and output on failure.

* cmd/utils/flags.go: Applying a String len guard for the gitCommit param of the NewApp()

* cmd/utils: remove redundant clause in if condition

all: switch gas limits from big.Int to uint64

This reverts commits 85a1eda5 (#15792) and c495bca4 (#15787)
because they introduce database writes during tracing.

* eth: uncaptialize tracer preimage error message

* eth: improve very important error message

All inputs are saved into history, including 'invalid' inputs.

This avoids setting CC for the go run invocation, which fails on go1.10.

Fixes #15744

* accounts/abi: handle named ouputs prefixed with underscores

* accounts/abi: handle collinding outputs for struct unpacks

* accounts: handle purely underscore output names

Initial implementation of ENR according to ethereum/EIPs#778

Fixes #15740

accounts/abi refactor

* accounts, consensus, core, eth: make chain maker consensus agnostic

* consensus, core: move CalcDifficulty to Engine interface

* consensus: add docs for calcDifficulty function

* consensus, core: minor comment fixups

* dashboard: minor design change

* dashboard: Flow integration, message API

* dashboard: minor polishes, exclude misspell linter

cmd/puppeth: fix faucet 502 error due to non-exposed HTTP port

New Whisper-level message introduced (PoW requirement),
corresponding logic added, plus some tests.

+ Reworked Method Unpack tests into more readable components
+ Added Method Unpack into slice test

+ adding missing comments
+ small cleanups which won't significantly change
  function body.
+ unify Method receiver name