fundingManager: persist state in opening process.

Persists the state of a channel opening process after funding
transaction is confirmed. This tracks the messages sent to
the peer such that the process can be continued in case of a
restart. Also introduces that the receiver side forgets about
channel if funding transaction is not confirmed in 48hrs.

lnd.go

@@ -140,9 +140,9 @@ func lndMain() error {
 			return server.genNodeAnnouncement(true)
 		},
 		SendAnnouncement: func(msg lnwire.Message) error {
-			server.discoverSrv.ProcessLocalAnnouncement(msg,
+			errChan := server.discoverSrv.ProcessLocalAnnouncement(msg,
 				idPrivKey.PubKey())
-			return nil
+			return <-errChan
 		},
 		ArbiterChan:    server.breachArbiter.newContracts,
 		SendToPeer:     server.sendToPeer,