Inverse of mortonEncode. Not needed by the read-only lookup path (which only ever encodes a query point), but used by the compressor and tests.
Column, 0 to 2^depth - 1, west to east.
Row, 0 to 2^depth - 1, south to north.
Inverse of mortonEncode. Not needed by the read-only lookup path (which only ever encodes a query point), but used by the compressor and tests.