Main view: add a splitted view to be able to show the map area under the browse view

Signed-off-by: Christophe <chris.chapuis@gmail.com>
Map: provide a zoomable, pan-able map view.

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>
Browser: when  viewing a photo, start with a fit-to-area zoom level.

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>