iPad: Make swipeable area full height

[philgyford]

Extend the swipeable area to the full height of the screen, so the footer is at the bottom of the screen when the article is short.

[philgyford]

Committed a change which makes the article body expand to fill the window if it's very short. But so far only on non-touch devices.

Need to find a way to trap when the same situation occurs on touch devices (current one doesn't seem to register), and do the same there.