closest_points_first: make 'radius' argument determine radius, not diameter.
Radius of 0 always returns center point.
This fixes 'V's range
find_nearby_items: truncate to screen size, restoring pre-closest_points_first
area.
add_items_or_charges: remove +1 from overflow radius, as closest_points_first(0,.. always returns center point.
Merge fixes to closest_points_first refactor.