relax SVN archive

Updated the parameter checks in the Relax_disp.test_hansen_cpmg_data_CR72_full system test.

Expanded the dispersion target function class docstring to include all current dispersion models.

Created the Relax_disp.test_hansen_cpmg_data_CR72_full system test for checking the 'CR72 full' model.

Simplified the test_hansen_cpmg_data_*() system tests by shifting most shared code into setup_hansen_cpmg_data().

Fix for the lib.dispersion.ns_2site_expanded module for the missing sqrt() function import.

Import fix for the 'NS 2-site expanded' dispersion model target function.

Updated the dispersion auto-analysis write_results() method for the recent model changes.

Large renaming of the relaxation dispersion models.

This includes both the analytic and numerical models. All of the models with separate R20A and R20B
parameters now have ' full' added to the end of the model name. And all of the corresponding
reduced models whereby R20A = R20B = R20 have had the trailing ' red' removed. All descriptions and
variable names have been updated to match.

Added the 'NS 2-site expanded' model to the relax user manual.

This is the numerical model for the 2-site Bloch-McConnell equations expanded using Maple by Nikolai
Skrynnikov. It originates as optimization function number 5 from the fitting_main_kex.py script
from Mathilde Lescanne, Paul Schanda, and Dominique Marion (see
http://thread.gmane.org/gmane.science.nmr.relax.devel/4138,
https://gna.org/task/?7712#comment2 and
https://gna.org/support/download.php?file_id=18262).

This commit follows step 2 of the relaxation dispersion model addition tutorial
(http://thread.gmane.org/gmane.science.nmr.relax.devel/3907).

Fix for the relax_disp.select_model user function for the 'NS 2-site expanded' model.

There is only one R20 parameter as R20A = R20B in this model.