Migrates the p2p connections to Protobuf. Supersedes #4800.

gogoproto's `NewDelimitedReader()` uses an internal buffer, which makes it unsuitable for reading individual messages from a shared reader (since any remaining data in the buffer will be discarded). We therefore add a new `protoio` package with an unbuffered `NewDelimitedReader()`. Additionally, the `NewDelimitedWriter()` returns the number of bytes written, and we've added `MarshalDelimited()` and `UnmarshalDelimited()`, to ease migration of existing code.

* format: add format cmd & goimport repo

- replaced format command
- added goimports to format command
- ran goimports

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* fix outliers & undo proto file changes

* Fix long line errors in abci, crypto, and libs packages

* Fix long lines in p2p and rpc packages

* Fix long lines in abci, state, and tools packages

* Fix long lines in behaviour and blockchain packages

* Fix long lines in cmd and config packages

* Begin fixing long lines in consensus package

* Finish fixing long lines in consensus package

* Add lll exclusion for lines containing URLs

* Fix long lines in crypto package

* Fix long lines in evidence package

* Fix long lines in mempool and node packages

* Fix long lines in libs package

* Fix long lines in lite package

* Fix new long line in node package

* Fix long lines in p2p package

* Ignore gocritic warning

* Fix long lines in privval package

* Fix long lines in rpc package

* Fix long lines in scripts package

* Fix long lines in state package

* Fix long lines in tools package

* Fix long lines in types package

* Enable lll linter

* Remove unnecessary type conversions

* Consolidate repeated strings into consts

* Clothe return statements

* Update blockchain/v1/reactor_fsm_test.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

This PR repairs linter errors seen when running the following commands:
golangci-lint run --no-config --disable-all=true --enable=unconvert
golangci-lint run --no-config --disable-all=true --enable=goconst
golangci-lint run --no-config --disable-all=true --enable=nakedret

Contributes to #3262

cleanup to add linter

    grpc change:
        https://godoc.org/google.golang.org/grpc#WithContextDialer
        https://godoc.org/google.golang.org/grpc#WithDialer
        grpc/grpc-go#2627
    prometheous change:
        due to UninstrumentedHandler, being deprecated in the future
    empty branch = empty if or else statement
        didn't delete them entirely but commented
        couldn't find a reason to have them
    could not replicate the issue #3406
        but if want to keep it commented then we should comment out the if statement as well

Refs #3262

This fixes two small bugs:

1) lite/dbprovider: return `ok` instead of true in parse* functions. It's weird that we're ignoring `ok` value before.
2) consensus/state: previously because of the shadowing we almost never output "Error with msg". Now we declare both `added` and `err` in the beginning of the function, so there's no shadowing.

in the attempt to fix https://circleci.com/gh/tendermint/tendermint/43165

also

    code is simplified by running gofmt -s .
    remove unused vars
    enable linters we're currently passing
    remove deprecated linters

* p2p/conn: FlushStop. Use in pex. Closes #2092

In seed mode, we call StopPeer immediately after Send.
Since flushing msgs to the peer happens in the background,
the peer connection is often closed before the messages are
actually sent out. The new FlushStop method allows all msgs
to first be written and flushed out on the conn before it is closed.

* fix dummy peer

* typo

* fixes from review

* more comments

* ensure pex doesn't call FlushStop more than once

FlushStop is not safe to call more than once,
but we call it from Receive in a go-routine so Receive
doesn't block.

To ensure we only call it once, we use the lastReceivedRequests
map - if an entry already exists, then FlushStop should already have
been called and we can return.

* catch up with amino changes in
https://github.com/tendermint/go-amino/pull/222

* WIP: update to amino v0.13.0

* update to fixed amino release

This reverts commit d02c5d1e30.

except now we calculate the max size using the maxPacketMsgSize()
function, which frees developers from having to know amino encoding
details.

plus, 10 additional bytes are added to leave the room for amino upgrades
(both making it more efficient / less efficient)

Fixes #1762#issuecomment-398940107

This reverts commit 96a3502

Fixes https://github.com/cosmos/cosmos-sdk/issues/1045

* extract stopPongTimer method
* TestMConnectionMultiplePings

See https://github.com/tendermint/tmlibs/issues/45

Fixes https://github.com/tendermint/tendermint/issues/851

Go1.9 and below's net.Pipe did not implement the SetDeadline
method so after commit
e2dd8ca946
this problem was exposed since now we check for errors.

To counter this problem, implement a simple composition for
net.Conn that always returns nil on SetDeadline instead of
tripping out.

Added build tags so that anyone using go1.10 when it is released
will be able to automatically use net.Pipe's net.Conns

also add a note to TestMConnectionSend