Cartesian product

This implementation of cartesian product includes two methods providing:
- the complete set resulting from the cartesian product of several subsets, returned as numeric matrix or two-dimensional cell,
- the successive tuples from the first index to the cardinal of the resulting set (without memory pre-allocation), returned numeric vector or one-dimensional cell.

These methods support subsets including both numeric and non-numeric elements, defined as numeric vectors or one-dimensional cells.