blockchain: add v2 reactor (#4361)

The work includes the reactor which ties together all the seperate routines involved in the design of the blockchain v2 refactor. This PR replaces #4067 which got far too large and messy after a failed attempt to rebase.

## Commits:

* Blockchainv 2 reactor:

	+ I cleaner copy of the work done in #4067 which fell too far behind and was a nightmare to rebase.
	+ The work includes the reactor which ties together all the seperate routines involved in the design of the blockchain v2 refactor.

* fixes after merge

* reorder iIO interface methodset

* change iO -> IO

* panic before send nil block

* rename switchToConsensus -> trySwitchToConsensus

* rename tdState -> tmState

* Update blockchain/v2/reactor.go

Co-Authored-By: Bot from GolangCI <42910462+golangcibot@users.noreply.github.com>

* remove peer when it sends a block unsolicited

* check for not ready in markReceived

* fix error

* fix the pcFinished event

* typo fix

* add documentation for processor fields

* simplify time.Since

* try and make the linter happy

* some doc updates

* fix channel diagram

* Update adr-043-blockchain-riri-org.md

* panic on nil switch

* liting fixes

* account for nil block in bBlockResponseMessage

* panic on duplicate block enqueued by processor

* linting

* goimport reactor_test.go

Co-authored-by: Bot from GolangCI <42910462+golangcibot@users.noreply.github.com>
Co-authored-by: Anca Zamfir <ancazamfir@users.noreply.github.com>
Co-authored-by: Marko <marbar3778@yahoo.com>
Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>

docs/architecture/adr-043-blockchain-riri-org.md

@@ -4,6 +4,7 @@
 * 18-06-2019: Initial draft
 * 08-07-2019: Reviewed
 * 29-11-2019: Implemented
+* 14-02-2020: Updated with the implementation details
 
 ## Context
 
@@ -27,7 +28,15 @@ This ADR is meant to specify the missing components and control necessary to ach
 Partition the responsibilities of the blockchain reactor into a set of components which communicate exclusively with events. Events will contain timestamps allowing each component to track time as internal state. The internal state will be mutated by a set of `handle*` which will produce event(s). The integration between components will happen in the reactor and reactor tests will then become integration tests between components. This design will be known as `v2`.
 
 ![v2 Blockchain Reactor Architecture
-Diagram](https://github.com/tendermint/tendermint/blob/f9e556481654a24aeb689bdadaf5eab3ccd66829/docs/architecture/img/blockchain-reactor-v2.png)
+Diagram](https://github.com/tendermint/tendermint/blob/584e67ac3fac220c5c3e0652e3582eca8231e814/docs/architecture/img/blockchain-reactor-v2.png)
+
+### Fast Sync Related Communication Channels
+
+The diagram below shows the fast sync routines and the types of channels and queues used to communicate with each other. 
+In addition the per reactor channels used by the sendRoutine to send messages over the Peer MConnection are shown.
+
+![v2 Blockchain Channels and Queues
+Diagram](https://github.com/tendermint/tendermint/blob/5cf570690f989646fb3b615b734da503f038891f/docs/architecture/img/blockchain-v2-channels.png)
 
 ### Reactor changes in detail