CHATHAMS IMPORTED: 29/4 --Glen
HB: mainland UPLOADED 2010-12-15 in changeset 6662772
RP: i think we only use layer=-1 for things underground
i would agree to using sub_sea=reef and natural=reef until one is approved
HB: added test for type==0.0; now looks good to me
HB 22 Aug 2012: updated to match new linz data release field names.