Landscape page detection

When reading in 2 page mode the large spreads get fit into the space of a regular vertical page. There should be some logic added to make it span the full screen instead based on image ratio.

assuming this is essentially the same as #184. the intention is that the two pages should fill the screen while maintaining their aspect ratio, but the sizing logic has some issues with it at the moment.

It's not, this is for sources that have spreads merged into one landscape image.

oh ok, I'll change the phrasing then