Transforms the voronoi_list into a vlist + bson_nb_voro_list, that are BSON-encodable.
        :return: [vlist, bson_nb_voro_list], to be used in the as_dict method

def to_bson_voronoi_list2(self):
        """
        Transforms the voronoi_list into a vlist + bson_nb_voro_list, that are BSON-encodable.
        :return: [vlist, bson_nb_voro_list], to be used in the as_dict method
        """
        bson_nb_voro_list2 = [None] * len(self.voronoi_list2)
        for ivoro, voro in enumerate(self.voronoi_list2):
            if voro is None or voro == 'None':
                continue
            site_voro = []
            # {'site': neighbors[nn[1]],
            #  'angle': sa,
            #  'distance': distances[nn[1]],
            #  'index': myindex}
            for nb_dict in voro:
                site = nb_dict['site']
                site_dict = {key: val for key, val in nb_dict.items() if key not in ['site']}
                #site_voro.append([ps.as_dict(), dd]) [float(c) for c in self.frac_coords]
                diff = site.frac_coords - self.structure[nb_dict['index']].frac_coords
                site_voro.append([[nb_dict['index'], [float(c) for c in diff]],
                                  site_dict])
            bson_nb_voro_list2[ivoro] = site_voro
        return bson_nb_voro_list2