Map datelines and wrapping

Currently tiles and rendering of actual maps themselves behaves well across the dateline and when the map wraps around. However, map objects, as they are rendered completely separately and by the QSG stack, are not so well-behaved. A full solution to this is complicated: the QSG stack, like the QGraphicsView stack in Mobility, is not designed to render the same object in multiple locations at once.

Currently objects such as polygons and polylines transform their coordinates using coordinateToScreenPosition. A possible workaround is altering coordinateToScreenPosition to return the nearest of the possible solutions, but more permanent strategies are also possible.