Complete reworking of the 'NS R1rho 2-site' dispersion model.

The original code of Nikolai Skrynnikov and Martin Tollinger has been modified to match the
behaviour of Dmitry Korzhnev's cpmg_fit software.  The equations from Korzhnev et al., JACS 2005
(http://dx.doi.org/10.1021/ja0446855) have been used for the initial magnetisation and the R1rho'
calculation.  All equations have been added to the manual to clarify the model.
Both relax and cpmg_fit input and output files for the Fyn SH3 R1rho data have been added.

This is for the 'TP02' model and 'NS R1rho 2-site' models.  The cpmg_fit results include source code
modifications to show the differences between the various 'corrections'.  The dispersion software
comparison file has been updated to include this data and to show the cpmg_fit verses relax
differences.
Updated the Relax_disp.test_tp02_data_to_ns_r1rho_2site system test.

This is for the fixes of the 'NS R1rho 2-site' dispersion model.