It's OK if the head will grow a little bit bigger, but we'll avoid
panic.

Refs #2703

Fixes #2740

* dedup with spec/abci/client-server

* fixup abci/readme

* link to getting started in abci/README

* https

* spec/abci: some deduplication

* docs: remove extraneous comment

* p2p: peer-id -> peer_id

* update changelog

This is a follow-up from https://github.com/tendermint/tendermint/pull/2724

Closes #2761

* Fix crypto/merkle ProofOperators.Verify to check bounds on keypath parts.

* Update PENDING

* only invoke InitWAL/CloseWAL if WalPath is not empty

Closes #2717

* panic if WAL is not initialized when calling CloseWAL

* add a changelog entry

* mempool: ErrPreCheck and more log info

* change Pre/PostCheckFunc to return errors

also, continue execution when checking txs in mempool_test if
err=PreCheckErr

if some process locks a block in round 0, then 0 is valid proposal.PO…

Merge pull request #2750 from tendermint/release/v0.26.0

Release/v0.26.0

* changelog_pending -> changelog

* update changelog

* update changelog

* update changelog and upgrading

* pubsub adr

Refs #951, #1879, #1880

* highlight question

* fix typos after Ismail's review

* validate reactor messages

Refs #2683

* validate blockchain messages

Refs #2683

* validate evidence messages

Refs #2683

* todo

* check ProposalPOL and signature sizes

* add a changelog entry

* check addr is valid when we add it to the addrbook

* validate incoming netAddr (not just nil check!)

* fixes after Bucky's review

* check timestamps

* beef up block#ValidateBasic

* move some checks into bcBlockResponseMessage

* update Gopkg.lock

Fix

```
grouped write of manifest, lock and vendor: failed to export github.com/tendermint/go-amino: fatal: failed to unpack tree object 6dcc6ddc14
```

by running `dep ensure -update`

* bump year since now we check it

* generate test/p2p/data on the fly using tendermint testnet

* allow sync chains older than 1 year

* use full path when creating a testnet

* move testnet gen to test/docker/Dockerfile

* relax LastCommitRound check

Refs #2737

* fix conflicts after merge

* add small comment

* some ValidateBasic updates

* fixes

* AppHash length is not fixed

* tmhash is fully 32 bytes. closes #1990

* AddressSize

* fix tests

* fix max sizes

* Fix general merkle keypath to start w/ last op's key

* Update CHANGELOG_PENDING.md

* Align Proposal message with spec

* Update spec

* Introduce EventValidBlock for informing peer about wanted block

* Merge with develop

* Add isCommit flag to NewValidBlock message

- Add test for the case of +2/3 Precommit from the previous round

* reorder fields

* add TestVoteString & update tests

* remove redundant info from Proposal.String()

* update spec

* revert changes on vote.String() -> more human friendly

* add year to log format

* update documentation

* Add ValidatorPubkeyTypes as a consensus param

Ref #2414

* update spec

* address anton's comment

* Switch to Validator and Validator Params

* Correct changelog entry

* Address bucky's comments!

* forgot to update changelog

* fix typo

* fix Params naming

original author of this file is @ebuchman:

https://github.com/ebuchman/fail-test

* WIP: update to amino 0.14.0

* update Changelog

* Update to latest amino version (v0.14.0)

This condition is really hard to get. Initially, lockedRound and
validRound are set to -1 as we start with round 0.

Refs #2702

Refs #2693

* 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

* types: test tm2pm on fully populated header

* upgrade for amino v0.13.0-rc0

* fix lint

* comment out final test

* use types.NewValidator

* node: set p2p.ProtocolVersion from state, not globals

* version bump

* update UPGRADING.md

* add missing pr numbers to changelog pending

* linkify changelog

* crypto: use stdlib crypto/rand. ref #2099

* comment

* types: first field in Canonical structs is Type

* fix spec

* update changelog, add authors script

* update changelog

* update changelog

* types: dont use SimpleHashFromMap for header. closes #1841

* changelog and spec

* comments

* p2p: bring back OriginalAddr

* p2p: set OriginalAddr

* update changelog

* abci: update RequestInfo for versions

* abci: update ResponseInfo for versions

* compile fix

* fix test

* software_version -> version

* comment fix

* update spec

* add test

* comments and fix test

It utilises async IO -> greater performance.

* p2p: add protocol Version to NodeInfo

* update node pkg. remove extraneous version files

* update changelog and docs

* fix test

* p2p: Version -> ProtocolVersion; more ValidateBasic and tests

* types: add Version to Header

* abci: add Version to Header

* state: add Version to State

* node: check software and state protocol versions match

* update changelog

* docs/spec: update for versions

* state: more tests

* remove TODOs

* remove empty test

* Change error output format

* Update tests

* 🤦

* apply suggestion

* [install scripts] update go version, remove upgrade

- upgrading OS is out of scope of installation scripts

* add missing log statement

Refs https://github.com/tendermint/tendermint/pull/2642#discussion_r225786794

Ref: #2563

I added IPC as an unencrypted alternative to SocketPV.

Besides I fixed the following aspects of SocketPV:

Added locking since we are operating on a single socket
The connection deadline is extended every time a successful packet exchange happens; otherwise the connection would always die permanently x seconds after the connection was established.
Added a ping/heartbeat mechanism to keep the connection alive; native TCP keepalives do not work in this use-case


* Extend the SecureConn socket to extend its deadline
* Add locking & ping/heartbeat packets to SocketPV
* Implement IPC PV and abstract socket signing
* Refactored IPC and SocketPV
* Implement @melekes comments
* Fixes to rebase