Add polyrhythms

Dear Noteflight team, 

I would request for you guys to add the polyrhythms feature. I like editing with your software, but please don't get me wrong, other music editors are also great. I am not saying yours is not good, but many other editors offer polyrhythms. I feel that this is a huge limitation, as this does not allow me to practice my scores properly. I hope you guys can try to make the polyrhythms out. Thanks!