Fix for Optimisation of Dr. Flemming Hansen's CPMG data to the 'NS CPMG 2-site star' dispersion model. 
Changed so assertAlmostEqual matches 2 digits.

Fix for bug #21322, (https://gna.org/bugs/?21322) - 5x Test suite fail for version 3.1.0
Reported for system CentOS 2.6.32-358.18.1.el6.x86_64.
Created the target functions for the 'NS MMQ 3-site' models.

This is for the 'NS MMQ 3-site' and 'NS MMQ 3-site (linear)' CPMG dispersion models.

This follows the tutorial for adding relaxation dispersion models at:
http://wiki.nmr-relax.com/Tutorial_for_adding_relaxation_dispersion_models_to_relax#The_target_function
Added the R2eff calculating functions for the 'NS MMQ 3-site' models to the relax library.

This is for the 'NS MMQ 3-site' and 'NS MMQ 3-site linear' CPMG dispersion models.

This follows the tutorial for adding relaxation dispersion models at:
http://wiki.nmr-relax.com/Tutorial_for_adding_relaxation_dispersion_models_to_relax#The_relax_library.