Incompatible change of jsa2mat when >2D

Change behavior of jsa2mat (and mat2jsa) to intuitive way.

    var ndarray: any[] = [
      [[10, 20, 30],
      [40, 50, 60]],

      [[70, 80, 90],
      [100, 110, 120]]
    ];
    mat = $M.jsa2mat(ndarray);

From this version,
mat(:, :, 1) is [[10, 20, 30], [40, 50, 60]]
mat(:, :, 2) is [[70, 80, 90], [100, 110, 120]]