* 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

* ed25519: use golang/x/crypto fork

* changelog

* gix GenerateFromPassword

* fixes from review

* Disable transitioning to new round upon 2/3+ of Precommit nils

Pull in ensureVote test function from https://github.com/tendermint/tendermint/pull/2132

* Add several ensureX test methods to wrap channel read with timeout

* Revert panic in tests

* Add additional metrics to p2p and consensus
Partially addresses https://github.com/cosmos/cosmos-sdk/issues/2169.
* WIP
* Updates from code review
* Updates from code review
* Add instrumentation namespace to configuration
* Fix test failure
* Updates from code review
* Add quotes
* Add atomic load
* Use storeint64
* Use addInt64 in writePacketMsgTo

* update secret connection to use a little endian encoded nonce

* update encoding of chunk length to be little endian, too

* update comment

* Change comment slightly to trigger circelci

* libs: Remove usage of custom Fmt, in favor of fmt.Sprintf

Closes #2193

* Fix bug that was masked by custom Fmt!

Signatures are now []byte, which saves on the number of bytes after
amino encoding

(squash this) address Ismail's comment

These test vectors are needed for comparison with the Rust implementation.
To implement this effectively, a "RandBool" method was added to cmn.Rand.

This now uses one hkdf on the X25519 shared secret to create
a key for the sender and receiver.
The hkdf call is now just called upon the computed shared
secret, since the shared secret is a function of the pubkeys.

The nonces now start at 0, as we are using chacha as a stream
cipher, and the sender and receiver now have different keys.

Generate keys with HKDF instead of hash functions, which provides better security properties.

Add xchacha20poly1305 to secret connection. (Due to rebasing, this code has been removed)

Currently the top level directory contains basically all of the code
for the crypto package. This PR moves the crypto code into submodules
in a similar manner to what `golang/x/crypto` does. This improves code
organization.

Ref discussion: https://github.com/tendermint/tendermint/pull/1966

Closes #1956

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

- re-add test
- add TODO
- err instead of panic where possible

This reverts commit 96a3502

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

As both configs are concerned with the p2p packaage and PeerConfig is
only used inside of the package there is no good reason to keep the
couple of fields separate, therefore it is collapsed into the more
general P2PConifg. This is a stepping stone towards a setup where the
components inside of p2p do not have any knowledge about the config.

follow-up to #1325

Closes #1227

* use increment and decrement operators.

* remove unnecessary else branches.

* fix package comment with leading space.

* fix receiver names.

* fix error strings.

* remove omittable code.

* remove redundant return statement.

* Revert changes (code is generated.)

* use cfg as receiver name for all config-related types.

* use lsi as the receiver name for the LastSignedInfo type.

* remove accidental binary

* docs: s/Dummy&dummy/KVStore&kvstore/g

* glide update to abci

* update abci import paths

* dummy begone, hello kvstore

* RequestInitChain needs genesisBytes

* glide update

Refs #1205

* extract stopPongTimer method
* TestMConnectionMultiplePings

Benchmark results:

```
BenchmarkSwitchBroadcast-2         30000             71275 ns/op
--- BENCH: BenchmarkSwitchBroadcast-2
        switch_test.go:339: success: 1, failure: 0
        switch_test.go:339: success: 100, failure: 0
        switch_test.go:339: success: 10000, failure: 0
        switch_test.go:339: success: 30000, failure: 0
```