Add ItemAppearing and ItemDisappearing events

[lucasbrahm]

This library is awesome, but currently was not enough to solve my problem. In my project, I need to dynamically fetch and add more data. I wanted that when user scrolls to the end (or nearly to the end) more data would be fetched and added to the ListView (infinite scroll ListView). An easy way to detect user scrolled to the end is to use ItemAppearing event of ListView, so when last item of ItemSource appears, we know it was scrolled to the end. My idea is create ItemAppearing and ItemDisappearing events in DataGrid which is going to be invoked from ListView events ItemAppearing and ItemDisappearing.