* cmd, eth: Added in the flag to step geth once sync based on input

* cmd, eth: 16400 Add an option to stop geth once in sync.

* cmd: 16400 Add an option to stop geth once in sync. WIP

* cmd/geth/main, les/fletcher: added in light mode support

* cmd/geth/main, les/fletcher: Cleaned Comments and code for light mode

* cmd: 16400 Fixed formatting issue and cleaned code

* cmd, eth, les: 16400 Fixed formatting issues

* cmd, eth, les: Performed gofmt to update formatting

* cmd, eth, les: Fixed bugs resulting formatting

* cmd/geth, eth/, les: switched to downloader event

* eth: Fixed styling and gen_config

* eth/: Fix nil error in config file

* cmd/geth: Updated countdown log

* les/fetcher.go: Removed depcreated channel

* eth/downloader.go: Removed deprecated select

* cmd/geth, cmd/utils: Fixed minor issues

* eth: Reverted config files to proper format

* eth: Fixed typo in config file

* cmd/geth, eth/down: Updated code to use header time stamp

* eth/downloader: Changed the time threshold to 10 minutes

* cmd/geth, eth/downloader: Updated downloading event to pass latest header

* cmd/geth: Updated main to use right timer object

* cmd/geth: Removed unused failed event

* cmd/geth: added in correct time field with type assertion

* cmd/geth, cmd/utils: Updated flag to use boolean

* cmd/geth, cmd/utils, eth/downloader: Cleaned up code based on recommendations

* cmd/geth: Removed unneeded import

* cmd/geth, eth/downloader: fixed event field and suggested changes

* cmd/geth, cmd/utils: Updated flag and linting issue

This change resolves multiple issues around handling of endpoint proofs.
The proof is now done separately for each IP and completing the proof
requires a matching ping hash.

Also remove waitping because it's equivalent to sleep. waitping was
slightly more efficient, but that may cause issues with findnode if
packets are reordered and the remote end sees findnode before pong.

Logging of received packets was hitherto done after handling the packet,
which meant that sent replies were logged before the packet that
generated them. This change splits up packet handling into 'preverify'
and 'handle'. The error from 'preverify' is logged, but 'handle' happens
after the message is logged. This fixes the order. Packet logs now
contain the node ID.

dput --passive should make repo pushes from Travis work again.
dput --no-upload-log works around an issue I had while uploading locally.

debuild -d says that debuild shouldn't check for build dependencies when
creating the source package. This option is needed to make builds work
in environments where the installed Go version doesn't match the
declared dependency in the source package.

This PR is replacing the metrics.influxdb.host.tag cmd-line flag with metrics.influxdb.tags - a comma-separated key/value tags, that are passed to the InfluxDB reporter, so that we can index measurements with multiple tags, and not just one host tag.

This will be useful for Swarm, where we want to index measurements not just with the host tag, but also with bzzkey and git commit version (for long-running deployments).

When some of the same messages are redefined anywhere in a Go project,
the protobuf package panics (see
https://github.com/golang/protobuf/issues/178).

Since this package is internal, there is no way to work around it, as
one cannot use it directly, but also cannot define the same messages.

There is no downside in making the package accessible.

Also say that cmd/bootnode is not for production use.

This change unbreaks the build and removes racy access to
disableCheckFreq. Even though the field is set while holding
the lock, it was read outside of the protected section.

swarm/storage: Fix race in TestLDBStoreCollectGarbage. Disable testLDBStoreRemoveThenCollectGarbage (#18512)

When opening the wallet, ask for passphrase as well as for the PIN
and return the relevant error (PIN/passphrase required). Open must then
be called again with either PIN or passphrase to advance the process.

This also updates the console bridge to support passphrase authentication.

For more information about this light client mode, read
https://hackmd.io/s/HJy7jjZpm

This replaces the GasSlowStep constant with params.ExpGas.
Both constants have value 10.

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: tune flaky tests that error in travis occasionally

* tests: formatting