Snav Imagemap Overlapped Areas

All areas of an image map should be reachable with spatial navigation, even if they overlap.

Manual test instruction: Ensure the img's default area gets visited first since it is the outermost area and closest to #first. From there, ensure that all internal areas are reachable too.

In general, if two areas are on the same distance from current focus F, SpatNav should prioritize the area that can absorb most of F's projection.

When looking for the closest "insider" (here, areas inside the focused img), SpatNav projects he img's edge onto each area. Here #poly wins over #circle because #poly's area absorbs more of the projection.