adding z-position, rotation and scale (incl x/y)  to view

View now has "z", "rotation" and "scale" (including "xscale" and "yscale") attributes that set the underlying 3D transform appropriately.   

Views also have the following methods to manipulate the z-position more simply: `moveToFront()`, `moveToBack()`, `moveInFrontOf(otherView)`, `moveBehind(otherView)`
It would be good to have the possible values documented...