send StatEvent on MessageEvent outgoing handler

avoids duplicate "not connected to any server" messages when attempting
to send messages while disconnected (because of the outgoing event loop
handling that message)

display.go

@@ -95,7 +95,6 @@ func (app *App) submitTextInput() {
 		}
 	} else {
 		app.outgoing <- MessageEvent(fmt.Sprintf("%s: %s", app.nick, app.input.String()))
-		app.outgoing <- StatEvent("")
 	}
 
 	app.input.SetContent("")

event.go

@@ -124,6 +124,7 @@ func (ev MessageEvent) HandleOutgoing(app *App) error {
 		return err
 	}
 	app.incoming <- SetLastEvent(num)
+	app.outgoing <- StatEvent("")
 
 	return nil
 }