changed to qualified column names for lat/lng, and added Array#sort_by_distance_from
changed to qualified column names for lat/lng, and added Array#sort_by_distance_from

git-svn-id: 1c28d5254c2506e18a70911f918dc097e3836272@36 9265c765-0211-4c68-b2df-6d1bd6e20c4d

isaacfeliu/geokit,jasherai/geokit