* go routines in blockchain reactor

* Added reference to the go routine diagram

* Initial commit

* cleanup

* Undo testing_logger change, committed by mistake

* Fix the test loggers

* pulled some fsm code into pool.go

* added pool tests

* changes to the design

added block requests under peer

moved the request trigger in the reactor poolRoutine, triggered now by a ticker

in general moved everything required for making block requests smarter in the poolRoutine

added a simple map of heights to keep track of what will need to be requested next

added a few more tests

* send errors to FSM in a different channel than blocks

send errors (RemovePeer) from switch on a different channel than the
one receiving blocks
renamed channels
added more pool tests

* more pool tests

* lint errors

* more tests

* more tests

* switch fast sync to new implementation

* fixed data race in tests

* cleanup

* finished fsm tests

* address golangci comments :)

* address golangci comments :)

* Added timeout on next block needed to advance

* updating docs and cleanup

* fix issue in test from previous cleanup

* cleanup

* Added termination scenarios, tests and more cleanup

* small fixes to adr, comments and cleanup

* Fix bug in sendRequest()

If we tried to send a request to a peer not present in the switch, a
missing continue statement caused the request to be blackholed in a peer
that was removed and never retried.

While this bug was manifesting, the reactor kept asking for other
blocks that would be stored and never consumed. Added the number of
unconsumed blocks in the math for requesting blocks ahead of current
processing height so eventually there will be no more blocks requested
until the already received ones are consumed.

* remove bpPeer's didTimeout field

* Use distinct err codes for peer timeout and FSM timeouts

* Don't allow peers to update with lower height

* review comments from Ethan and Zarko

* some cleanup, renaming, comments

* Move block execution in separate goroutine

* Remove pool's numPending

* review comments

* fix lint, remove old blockchain reactor and duplicates in fsm tests

* small reorg around peer after review comments

* add the reactor spec

* verify block only once

* review comments

* change to int for max number of pending requests

* cleanup and godoc

* Add configuration flag fast sync version

* golangci fixes

* fix config template

* move both reactor versions under blockchain

* cleanup, golint, renaming stuff

* updated documentation, fixed more golint warnings

* integrate with behavior package

* sync with master

* gofmt

* add changelog_pending entry

* move to improvments

* suggestion to changelog entry

* blockchain: update the maxHeight when a peer is removed

Refs #2699

* add a changelog entry

* make linter pass

* fix fastsync may stuck by a wrong block

* fixes from updates

* fixes from review

* Align spec with the changes

* fmt

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 commit switches all usage of math/rand to cmn's rand. The only
exceptions are within the random file itself, the tools package, and the
crypto package. In tools you don't want it to lock between the go-routines.
The crypto package doesn't use it so the crypto package have no other
dependencies within tendermint/tendermint for easier portability.

Crypto/rand usage is unadjusted.

Closes #1343

make BlockMeta Header a non-pointer

Refs #693

This reverts commit d02c5d1e30.

This reverts commit 96a3502

uint64 is considered dangerous. the details will follow in a blog post.

See https://github.com/tendermint/tmlibs/issues/45

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