Added more params, update scene after size change

Added extensive list of params to allow tight control of setup -
options for: overriding screen size, forcing minimum border, scale to
pixel multiple only (1->2 pixels, 1->3 pixels, etc.) Improved docs.
Allowed applyToScene() to be called again to allow scene to update
itself if screen size changes (e.g. rotation or Android/desktop going
in-out of full screen)