## PR

This PR introduces a fundamental breaking change to the structure of ABCI response and tx tags and the way they're processed. Namely, the SDK can support more complex and aggregated events for distribution and slashing. In addition, block responses can include duplicate keys in events.

    Implement new Event type. An event has a type and a list of KV pairs (ie. list-of-lists). Typical events may look like:

"rewards": [{"amount": "5000uatom", "validator": "...", "recipient": "..."}]
"sender": [{"address": "...", "balance": "100uatom"}]

The events are indexed by {even.type}.{even.attribute[i].key}/.... In this case a client would subscribe or query for rewards.recipient='...'

    ABCI response types and related types now include Events []Event instead of Tags []cmn.KVPair.
    PubSub logic now publishes/matches against map[string][]string instead of map[string]string to support duplicate keys in response events (from #1385). A match is successful if the value is found in the slice of strings.

closes: #1859
closes: #2905

## Commits:

* Implement Event ABCI type and updates responses to use events

* Update messages_test.go

* Update kvstore.go

* Update event_bus.go

* Update subscription.go

* Update pubsub.go

* Update kvstore.go

* Update query logic to handle slice of strings in events

* Update Empty#Matches and unit tests

* Update pubsub logic

* Update EventBus#Publish

* Update kv tx indexer

* Update godocs

* Update ResultEvent to use slice of strings; update RPC

* Update more tests

* Update abci.md

* Check for key in validateAndStringifyEvents

* Fix KV indexer to skip empty keys

* Fix linting errors

* Update CHANGELOG_PENDING.md

* Update docs/spec/abci/abci.md

Co-Authored-By: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

* Update abci/types/types.proto

Co-Authored-By: Ethan Buchman <ethan@coinculture.info>

* Update docs/spec/abci/abci.md

Co-Authored-By: Ethan Buchman <ethan@coinculture.info>

* Update libs/pubsub/query/query.go

Co-Authored-By: Ethan Buchman <ethan@coinculture.info>

* Update match function to match if ANY value matches

* Implement TestSubscribeDuplicateKeys

* Update TestMatches to include multi-key test cases

* Update events.go

* Update Query interface godoc

* Update match godoc

* Add godoc for matchValue

* DRY-up tx indexing

* Return error from PublishWithEvents in EventBus#Publish

* Update PublishEventNewBlockHeader to return an error

* Fix build

* Update events doc in ABCI

* Update ABCI events godoc

* Implement TestEventBusPublishEventTxDuplicateKeys

* Update TestSubscribeDuplicateKeys to be table-driven

* Remove mod file

* Remove markdown from events godoc

* Implement TestTxSearchDeprecatedIndexing test

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

Fixes #2912

* kv indexer: add separator to start key when matching ranges

to avoid including false positives

Refs #2908

* refactor code

* add a test case

Fixes #2908

Fixes #2775

otherwise we're benchmarking overriding single key (because hash stays
the same!)

* remove gogoproto from tools

because it's not a binary

* update protobuf version to 3.6.1 in `make get_protoc`

* update libs/common/types.pb.go and rpc/grpc/types.pb.go

* fix app tests

Refs #1861

We don't use the fee field and its likely just confusing.

We can add backwards compatible priority (instead of fee) later.

Note priority is better than fee because it lets the app do the math on how to rank order transactions, rather than forcing that into tendermint (ie. if we return fee, priority would be fee/gas)

This reverts commit d02c5d1e30.

This reverts commit 96a3502

Refs #847

* 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.

before we're using IteratePrefix, which is wrong because we want full
range, not just "account.number=1".

I assume there is a deeper issue with how UnmarshalBinary works in
go-amino (i.e., when loading array of some objects, the empty array
becomes []object{nil}). Note when Marshaling, the object is nil.

encoded as %s. not sure this will work with raw bytes

NOTE we only updating for tmlibs and abci

and send them along with predefined

save transactions to blockstore

move to a separate module

benchmark KVIndexer

batch write transactions

Benchmarks:

```
BenchmarkKVIndexerIndex-2         100000            516300 ns/op
PASS
ok      github.com/tendermint/tendermint/blockchain/tx  56.506s

5,16 s for 10000 transactions
1 s for 2000 transactions
```

```
BenchmarkKVIndexerIndex-2       h 3000000             8622 ns/op
PASS
ok      github.com/tendermint/tendermint/blockchain/tx  34.210s

86 ms for 10000 transactions
16 ms for 2000 transactions
```

```
BenchmarkKVIndexerIndex1-2               5000000              7160 ns/op
BenchmarkKVIndexerIndex500-2               20000           1750411 ns/op
BenchmarkKVIndexerIndex1000-2              10000           3573973 ns/op
BenchmarkKVIndexerIndex2000-2               5000           7836851 ns/op
BenchmarkKVIndexerIndex10000-2              1000          33438980 ns/op
PASS
ok      github.com/tendermint/tendermint/blockchain/tx  209.482s

7,8 ms for 2000 transactions
```

[state] write test for ApplyBlock

review comments

- move txindexer to state
- fix type

save Tx Index as well

do not store tx itself in the result