This issue is related to #3107
This is a first renaming/refactoring step before reworking and removing heartbeats.
As discussed with @Liamsi , we preferred to go for a couple of independent and separate PRs to simplify review work.

The changes:

    Help to clarify the relation between the validator and remote signer endpoints
    Differentiate between timeouts and deadlines
    Prepare to encapsulate networking related code behind RemoteSigner in the next PR

My intention is to separate and encapsulate the "network related" code from the actual signer.

SignerRemote ---(uses/contains)--> SignerValidatorEndpoint <--(connects to)--> SignerServiceEndpoint ---> SignerService (future.. not here yet but would like to decouple too)

All reconnection/heartbeat/whatever code goes in the endpoints. Signer[Remote/Service] do not need to know about that.

I agree Endpoint may not be the perfect name. I tried to find something "Go-ish" enough. It is a common name in go-kit, kubernetes, etc.

Right now:
SignerValidatorEndpoint:

    handles the listener
    contains SignerRemote
    Implements the PrivValidator interface
    connects and sets a connection object in a contained SignerRemote
    delegates PrivValidator some calls to SignerRemote which in turn uses the conn object that was set externally

SignerRemote:

    Implements the PrivValidator interface
    read/writes from a connection object directly
    handles heartbeats

SignerServiceEndpoint:

    Does most things in a single place
    delegates to a PrivValidator IIRC.

* cleanup

* Refactoring step 1

* Refactoring step 2

* move messages to another file

* mark for future work / next steps

* mark deprecated classes in docs

* Fix linter problems

* additional linter fixes

* libs/common: TrapSignal accepts logger as a first parameter

 and does not block anymore
* previously it was dumping "captured ..." msg to os.Stdout
* TrapSignal should not be responsible for blocking thread of execution

Refs #3238

* exit with zero (0) code upon receiving SIGTERM/SIGINT

Refs #3238

* fix formatting in docs/app-dev/abci-cli.md

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

* fix formatting in docs/app-dev/abci-cli.md

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

https://github.com/tendermint/tendermint/pull/2923#pullrequestreview-192065694

* Close and recreate a RemoteSigner on err

* Update changelog

* Address Anton's comments / suggestions:

 - update changelog
 - restart TCPVal
 - shut down on `ErrUnexpectedResponse`

* re-init remote signer client with fresh connection if Ping fails

- add/update TODOs in secret connection
- rename tcp.go -> tcp_client.go, same with ipc to clarify their purpose

* account for `conn returned by waitConnection can be `nil`

- also add TODO about RemoteSigner conn field

* Tests for retrying: IPC / TCP

 - shorter info log on success
 - set conn and use it in tests to close conn

* Tests for retrying: IPC / TCP

 - shorter info log on success
 - set conn and use it in tests to close conn
 - add rwmutex for conn field in IPC

* comments and doc.go

* fix ipc tests. fixes #2677

* use constants for tests

* cleanup some error statements

* fixes #2784, race in tests

* remove print statement

* minor fixes from review

* update comment on sts spec

* cosmetics

* p2p/conn: add failing tests

* p2p/conn: make SecretConnection thread safe

* changelog

* IPCVal signer refactor

- use a .reset() method
- don't use embedded RemoteSignerClient
- guard RemoteSignerClient with mutex
- drop the .conn
- expose Close() on RemoteSignerClient

* apply IPCVal refactor to TCPVal

* remove mtx from RemoteSignerClient

* consolidate IPCVal and TCPVal, fixes #3104

- done in tcp_client.go
- now called SocketVal
- takes a listener in the constructor
- make tcpListener and unixListener contain all the differences

* delete ipc files

* introduce unix and tcp dialer for RemoteSigner

* rename files

- drop tcp_ prefix
- rename priv_validator.go to file.go

* bring back listener options

* fix node

* fix priv_val_server

* fix node test

* minor cleanup and comments

* split immutable and mutable parts of priv_validator.json

* fix bugs

* minor changes

* retrig test

* delete scripts/wire2amino.go

* fix test

* fixes from review

* privval: remove mtx

* rearrange priv_validator.go

* upgrade path

* write tests for the upgrade

* fix for unsafe_reset_all

* add test

* add reset test

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.

This reverts commit 96a3502

* Switch ports 466xx to be 266xx
This is done so the default ports aren't in the linux kernel's default ephemeral port range.

* Update ABCI import

* Bump cache on circleci

* Get more verbose output for debugging

* Bump abci dependency

* Fix accidental change of a block header's hash

* pin abci release

This is a maintenance change to move the private validator package out
of the types and to a top-level location. There is no good reason to
keep it under the types and it will more clearly coommunicate where
additions related to the privval belong. It leaves the interface and the
mock in types for now as it would introduce circular dependency between
privval and types, this should be resolved eventually.

* mv priv_validator to privval pkg
* use consistent `privval` as import

Follow-up to #1255

Follow-up to feedback from #1286, this change simplifies the connection
handling in the SocketClient and makes the communication via TCP more
robust. It introduces the tcpTimeoutListener to encapsulate accept and
i/o timeout handling as well as connection keep-alive, this type could
likely be upgraded to handle more fine-grained tuning of the tcp stack
(linger, nodelay, etc.) according to the properties we desire. The same
methods should be applied to the RemoteSigner which will be overhauled
when the priv_val_server is fleshed out.

* require private key
* simplify connect logic
* break out conn upgrades to tcpTimeoutListener
* extend test coverage and simplify component setup

Follow-up to #1255 aligning with the expectation that the external
signing process connects to the node. The SocketClient will block on
start until one connection has been established, support for multiple
signers connected simultaneously is a planned future extension.

* SocketClient accepts connection
* PrivValSocketServer renamed to RemoteSigner
* extend tests