`rray_cube()` integer overflow

[DavisVaughan]

Use xt::cube(xt::cast<double>(x)) which only results in 1 memory allocation but still has the nice properties of not integer overflowing. Base R always returns a double anyways

[DavisVaughan]

template <typename T>
Rcpp::RObject rray__cube_impl(const xt::rarray<T>& x) {
  xt::rarray<double> xt_out = xt::cube(xt::cast<double>(x));

  Rcpp::RObject out = SEXP(xt_out);
  out.attr("dimnames") = rray__dim_names(SEXP(x));

  return out;
}

Rcpp::RObject rray__cube_impl(const xt::rarray<double>& x) {
  xt::rarray<double> xt_out = xt::cube(x);

  Rcpp::RObject out = SEXP(xt_out);
  out.attr("dimnames") = rray__dim_names(SEXP(x));

  return out;
}

// [[Rcpp::export(rng = false)]]
Rcpp::RObject rray__cube(Rcpp::RObject x) {
  DISPATCH_UNARY(rray__cube_impl, x);
}