Created the target functions for the 'NS R1rho 3-site' models.

This is for the 'NS R1rho 3-site' and 'NS R1rho 3-site linear' 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 R1rho 3-site' models to the relax library.

This is for the 'NS R1rho 3-site' and 'NS R1rho 3-site linear' 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.
Fix for GUI text string for the select radio button, reading spins from a spectrum formatted file.

Work in progress for Support Request #3044, (https://gna.org/support/index.php?3044) - Load spins from SPARKY list.
Bug fix for the new 'NS R1rho 3-site' dispersion models - the Y and Z initial magnetisations were switched.

This is for the 'NS R1rho 3-site' and 'NS R1rho 3-site linear' 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#Debugging.
Added cpmg_fit results for the program modified to turn off the PEAK_SHIFT flag.

These are the results which should most closely match the relax results.  This is for the simulated
R1rho data for the 'NS R1rho 3-site linear' model.
Fix for the MODEL_NS_R1RHO_3SITE_LINEAR dispersion variable.

The model name was not correct.
Turned off the dw dispersion parameter constraints for the 'NS R1rho 3-site' models.
Missing import from the previous commit.
Added the 'NS R1rho 3-site' models to the dispersion auto-analysis.

This is for the 'NS R1rho 3-site' and 'NS R1rho 3-site linear' 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_auto-analysis.
Added the 'NS R1rho 3-site' models to the GUI model list.

This is for the 'NS R1rho 3-site' and 'NS R1rho 3-site linear' 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_GUI.
Removed the pC <= pB constraint from the 3-site dispersion models.

This is important for the linear models where a violation of this constraint is reasonable.  This
has been replaced by the pC <= pA constraint.