p2p: peer state init too late and pex message too soon (#3634)

* fix peer state init to late

Peer does not have a state yet. We set it in AddPeer.
We need an new interface before mconnection is started

* pex message to soon

fix reconnection pex send too fast,
error is caused lastReceivedRequests is still
not deleted when a peer reconnected

* add test case for initpeer

* add prove case

* remove potentially infinite loop

* Update consensus/reactor.go

Co-Authored-By: guagualvcha <baifudong@lancai.cn>

* Update consensus/reactor_test.go

Co-Authored-By: guagualvcha <baifudong@lancai.cn>

* document Reactor interface better

* refactor TestReactorReceiveDoesNotPanicIfAddPeerHasntBeenCalledYet

* fix merge conflicts

* blockchain: remove peer's ID from the pool in InitPeer

Refs #3338

* pex: resetPeersRequestsInfo both upon InitPeer and RemovePeer

* ensure RemovePeer is always called before InitPeer

by removing the peer from the switch last (after we've stopped it and
removed from all reactors)

* add some comments for ConsensusReactor#InitPeer

* fix pex reactor

* format code

* fix spelling

* update changelog

* remove unused methods

* do not clear lastReceivedRequests upon error

only in RemovePeer

* call InitPeer before we start the peer!

* add a comment to InitPeer

* write a test

* use waitUntilSwitchHasAtLeastNPeers func

* bring back timeouts

* Test to ensure Receive panics if InitPeer has not been called

consensus/byzantine_test.go

@@ -270,3 +270,4 @@ func (br *ByzantineReactor) RemovePeer(peer p2p.Peer, reason interface{}) {
 func (br *ByzantineReactor) Receive(chID byte, peer p2p.Peer, msgBytes []byte) {
 	br.reactor.Receive(chID, peer, msgBytes)
 }
+func (br *ByzantineReactor) InitPeer(peer p2p.Peer) p2p.Peer { return peer }