Generalize make_matrices

[qbarthelemy]

This PR:

• adds kinds = "sym" and "herm" in make_matrices to respectively generate symmetric and Hermitian matrices;
• adds new parameters eigvecs_mean and eigvecs_std to make_matrices,
  controlling the mean and standard deviation of the normal distribution used to draw eigen vectors;
• deprecates generate_random_spd_matrix, because redundant with make_matrices;
• adds missing tests for make_outliers;
• improves documentation for dataset module;
• completes tests for rjd and uwedge, supporting symmetric matrices.