function readCoordIJ(cAddress) {
    return {
        i: C.getValue(cAddress, 'i32'),
        j: C.getValue(cAddress + SZ_INT, 'i32')
    };
}
Read a CoordIJ from C and return an {i, j} pair.
@private
@param  {number} cAddress    Pointer to C struct
@return {CoordIJ}            {i, j} pair