Draft: PageTurnLayout becomes ViewPager with draw 

This branch keeps the draw function in the ViewPager (former PageTurnLayout) which means it might be more successful than #6 in getting the curl animation to become visible. On the other hand, it has to use it's own page turn detection logic (maybe built on the onPageScrolled rather on than onTouch) which was the part that   never got triggered on a Nexus 10 in a case without pull #3