* p2p: panic on transport error

Addresses #2823. Currently, the acceptRoutine exits if the transport returns
an error trying to accept a new connection. Once this happens, the node
can't accept any new connections. So here, we panic instead. While we
could potentially be more intelligent by rerunning the acceptRoutine, the
error may indicate something more fundamental (eg. file desriptor limit)
that requires a restart anyways. We can leave it to process managers to
handle that restart, and notify operators about the panic.

* changelog

* update changelog

* changelog, upgrading, version

* prepare changelog

* linkify changelog

* changelog and version

* update changelog

* update CONTRIBUTING with notes on CHANGELOG

* update changelog

* changelog and version

* add adr-034

* update changelog

* minor changes

* do some refactor

* changelog and version

* fix changelog

* Require addressbook to only store addresses with valid ID

* Do not shut down peer immediately after sending pex addrs in SeedMode

* p2p: fix #2773

* seed mode: use go-routine to sleep before stopping peer

* changelog_pending -> changelog

* update changelog

* update changelog

* update changelog and upgrading

* libs/autofile: bring back loops

* changelog, version

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)

Refs #1706

before: 1.000000003s
after: 3.000000000s

Refs #2027

* update changelog

* txAvailable is always true

Refs #2021, #1920

* remove debug message

No additional value. `enterPropose` log message should be enough.

Refs #2021, #1920

* #1920 try to fix race condition on proposal height for published txs

- related to create_empty_blocks=false
- published height for accepted tx can be wrong (too low)
- use the actual mempool height + 1 for the proposal
- expose Height() on mempool

* #1920 add initial test for mempool.Height()

- not sure how to test the lock
- can the mutex reference be of type Locker?
-- this way, we can use a "mock" of the mutex to test triggering

* #1920 use the ConsensusState height in favor of mempool

- gets rid of indirections
- doesn't need any "+1" magic

* #1920 cosmetic

- if we use cs.Height, it's enough to evaluate right before propose

* #1920 cleanup TODO and non-needed code

* #1920 add changelog entry

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

gogoproto.nullable compatible with GRPC downstream of ABCI and libs
protbuf types

We were computing these functions incorrectly.
I'm not sure what distribution these numbers are, but it isn't the
normal exponential distribution. (We're making the probability of
getting a number of a particular bitlength equal, but the number in
that bitlength thats gets chosen is uniformly chosen)

We weren't using these functions anywhere in our codebase, and they
had a nomenclature error. (There aren't exponentially distributed
integers, instead they would be geometrically distributed)

* config: 10x default send/recv rate

This increases the default send/recv rate from 512 kB/s to 5.12 mB/s

Closes #1752

* Fix typo

* tools/tm-bench: Don't count the first block if its empty

* Try melekes suggestion

* Fix getting the start time so the first block is no longer empty

* Fix changelog entry

* Make code smell better

* tools/tmbench: Fix the end time being used for statistics calculation

Previously we were using the time at which all connections closed in statistics, not
the time after {duration} seconds.

* Use waitgroups for starting up

Previously we were using the time at which all connections closed in statistics, not
the time after {duration} seconds.

* Add test showing normal Sync call

* Show hanging response if server dies during BeginBlock

* Flush all in-flight requests on shutdown, not just pending requests

* Add bugfix to CHANGELOG

This reverts commit d02c5d1e30.

* limit the number of requests in flights for Prometheus server

Closes #1804

Default to 1 because usually there's just one collector.

* config: Up default for prom connections

Refs #1901

* include ecosystem.json

* update changelog

* also include zarko's interview

Closes #1901