Draft: View pager with a page transform without draw 

This is probably the most fruitful branch which I will track here, although I'll probably close the pull request since it's a lot of code changes but maybe something you can build on when you do the refactor. This branch takes the existing PageTurnLayout and converts it into a PageTransform.

* I tried using the current draw logic to get the page curl animation but wasn't able to get the draw to have a visual result. I set it up with some debugging for you with some logging of the x position while the user swipes so maybe you could find a way to get it to draw. https://github.com/cesine/book-animation/tree/viewPager

* So I could return to our issue https://github.com/iLanguage/OPrime/issues/45 I combined two transforms (depth and flip) to achieve a "page turn-like transformation" but not as visually pleasing as an actual curl, but at least makes it possible for us to continue on what we needed to do...  https://github.com/cesine/book-animation/tree/pageTransformer
These interior views are not being used right now, although ideally i would make it backward compatibale so that users could use a page or this method of specifying the views in the PageViewer..