Fix for system tests:
F 1.34 s for Relax_disp.test_cpmg_synthetic_ns3d_to_b14
F 0.78 s for Relax_disp.test_cpmg_synthetic_ns3d_to_cr72
F 3.74 s for Relax_disp.test_cpmg_synthetic_ns3d_to_cr72_noise_cluster
The number of dotting with Mint, should corespond to the power.
Task #7807 (https://gna.org/task/index.php?7807): Speed-up of dispersion models for Clustered analysis.
