[tm-monitor] fix blocking issue

as you can see the mistake is that we listen for quit instead of closing
it.

tm-monitor/eventmeter/eventmeter.go

@@ -140,8 +140,9 @@ func (em *EventMeter) Start() error {
 	return nil
 }
 
+// Stop stops the EventMeter.
 func (em *EventMeter) Stop() {
-	<-em.quit
+	close(em.quit)
 
 	em.RegisterDisconnectCallback(nil) // so we don't try and reconnect
 	em.wsc.Stop()                      // close(wsc.Quit)

tm-monitor/monitor/node.go

@@ -121,12 +121,7 @@ func (n *Node) Start() error {
 func (n *Node) Stop() {
 	n.Online = false
 
-	n.em.RegisterLatencyCallback(nil)
-	n.em.Unsubscribe(tmtypes.EventStringNewBlockHeader())
-	n.em.RegisterDisconnectCallback(nil)
-
-	// FIXME stop blocks at event_meter.go:140
-	// n.em.Stop()
+	n.em.Stop()
 
 	close(n.quit)
 }