Creates a random set of points distributed in four clusters in * 3D space with centroids at the points * * \f$(0,5, 0.5, 0.5)\f$ * * \f$(0,5,-0.5, -0.5)\f$ * * \f$(-0,5, 0.5, 0.5)\f$ * * \f$(-0,5,-0.5, -0.5)\f$ * * \param[out] data matrix to store data in * \param[in] N number of points required */