`z5::multiarray::{read,write}Subarray` does not work correctly for `xt::rarray`

[gdkrmr]

The following does not read or write the data correctly when complete chunks are read in, as in #10:

zarr-R/src/xtensor-read.cpp

Line 167 in 31c4176

// xt::rarray<double> array(shape_);

    // xt::rarray<double> array(shape_);
    // z5::multiarray::readSubarray<double>(*ds, array, offset_.begin());
    // res = wrap(array);

zarr-R/src/xtensor-write.cpp

Line 156 in 31c4176

// case z5::types::float64: { z5::multiarray::writeSubarray<double>(*ds, data_, offset_.begin()); break;};

    // case z5::types::int32:   { z5::multiarray::writeSubarray<int32_t>(*ds, data_, offset_.begin()); break;};

[gdkrmr]

TODO: figure out if this is really an issue or xtensor-r or just me using it the wrong way.