This applies spec changes from ethereum/EIPs#1049 and adds support for
pluggable identity schemes.

Some care has been taken to make the "v4" scheme standalone. It uses
public APIs only and could be moved out of package enr at any time.

A couple of minor changes were needed to make identity schemes work:

- The sequence number is now updated in Set instead of when signing.
- Record is now copy-safe, i.e. calling Set on a shallow copy doesn't
  modify the record it was copied from.

Peer.run was discarding the reason for disconnection sent to the disc
channel by Disconnect.

The parameter `rand` is unused in `PrivateKey.Decrypt`. Decryption in
the ECIES encryption scheme is deterministic, so randomness isn't
needed.

* go-metrics: fork library and introduce ResettingTimer and InfluxDB reporter.

* vendor: change nonsense/go-metrics to ethersphere/go-metrics

* go-metrics: add tests. move ResettingTimer logic from reporter to type.

* all, metrics: pull in metrics package in go-ethereum

* metrics/test: make sure metrics are enabled for tests

* metrics: apply gosimple rules

* metrics/exp, internal/debug: init expvar endpoint when starting pprof server

* internal/debug: tiny comment formatting fix

* p2p: remove unused code

* p2p: remove unused imports

This change removes a peer information from dialing history
when peer is removed from static list. It allows to force a
server to re-dial concrete peer if it is needed.

In our case we are running geth node on mobile devices, and
it is common for a network connection to flap on mobile.
Almost every time it flaps or network connection is changed
from cellular to wifi peers are disconnected with read
timeout. And usually it takes 30 seconds (default expiration
timeout) to recover connection with static peers after
connectivity is restored.

This change allows us to reconnect with peers almost
immediately and it seems harmless enough.

Handle all expectations in ProtocolSession.TestExchanges in any
order that are received.

I forgot to change the check in udp.go when I changed Table.bond to be
based on lastPong instead of node presence in db. Rename lastPong to
bondTime and add hasBond so it's clearer what this DB key is used for
now.

* cmd,node,rpc: add allowedHosts to prevent dns rebinding attacks

* p2p,node: Fix bug with dumpconfig introduced in r54aeb8e4c0bb9f0e7a6c67258af67df3b266af3d

* rpc: add wildcard support for rpcallowedhosts + go fmt

* cmd/geth, cmd/utils, node, rpc: ignore direct ip(v4/6) addresses in rpc virtual hostnames check

* http, rpc, utils: make vhosts into map, address review concerns

* node: change log messages to use geth standard (not sprintf)

* rpc: fix spelling

* p2p: add DialRatio for configuration of inbound vs. dialed connections

* p2p: add connection flags to PeerInfo

* p2p/netutil: add SameNet, DistinctNetSet

* p2p/discover: improve revalidation and seeding

This changes node revalidation to be periodic instead of on-demand. This
should prevent issues where dead nodes get stuck in closer buckets
because no other node will ever come along to replace them.

Every 5 seconds (on average), the last node in a random bucket is
checked and moved to the front of the bucket if it is still responding.
If revalidation fails, the last node is replaced by an entry of the
'replacement list' containing recently-seen nodes.

Most close buckets are removed because it's very unlikely we'll ever
encounter a node that would fall into any of those buckets.

Table seeding is also improved: we now require a few minutes of table
membership before considering a node as a potential seed node. This
should make it less likely to store short-lived nodes as potential
seeds.

* p2p/discover: fix nits in UDP transport

We would skip sending neighbors replies if there were fewer than
maxNeighbors results and CheckRelayIP returned an error for the last
one. While here, also resolve a TODO about pong reply tokens.

* p2p/discv5: add query delay, fix node address update logic, retry refresh if empty

* p2p/discv5: remove unnecessary ping before topic query

* p2p/discv5: do not filter local address from topicNodes

* p2p/discv5: remove canQuery()

* p2p/discv5: gofmt

This commit affects p2p/discv5 "topic discovery" by running it on
the same UDP port where the old discovery works. This is realized
by giving an "unhandled" packet channel to the old v4 discovery
packet handler where all invalid packets are sent. These packets
are then processed by v5. v5 packets are always invalid when
interpreted by v4 and vice versa. This is ensured by adding one
to the first byte of the packet hash in v5 packets.

DiscoveryV5Bootnodes is also changed to point to new bootnodes
that are implementing the changed packet format with modified
hash. Existing and new v5 bootnodes are both running on different
ports ATM.

* 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

Initial implementation of ENR according to ethereum/EIPs#778

This commit adds mocker functionality to p2p/simulations. A
mocker allows to starting/stopping of nodes via the HTTP API.

p2p/simulations: introduce dialBan

- Refactor simulations/network connection getters to support
  avoiding simultaneous dials between two peers If two peers dial
  simultaneously, the connection will be dropped to help avoid
  that, we essentially lock the connection object with a
  timestamp which serves as a ban on dialing for a period of time
  (dialBanTimeout).

- The connection getter InitConn can be wrapped and passed to the
  nodes via adapters.NodeConfig#Reachable field and then used by
  the respective services when they initiate connections. This
  massively stablise the emerging connectivity when running with
  hundreds of nodes bootstrapping a network.

p2p: add Inbound public method to p2p.Peer

p2p/simulations: Add server id to logs to support debugging
in-memory network simulations when multiple peers are logging.

p2p: SetupConn now returns error. The dialer checks the error and
only calls resolve if the actual TCP dial fails.

* build: enable unconvert linter

 - fixes #15453
 - update code base for failing cases

* cmd/puppeth: replace syscall.Stdin with os.Stdin.Fd() for unconvert linter

Fixes #1024

* p2p: snappy encoding for devp2p (version bump to 5)

* p2p: remove lazy decompression, enforce 16MB limit

This commit introduces a network simulation framework which
can be used to run simulated networks of devp2p nodes. The
intention is to use this for testing protocols, performing
benchmarks and visualising emergent network behaviour.