relax SVN archive

Fix for the 'MQ CR72' dispersion model target function.

The correct R20 values are now extracted from the parameter vector.

Removed a latent bug in the 'MMQ 2-site' dispersion model.

This was not being seen but might have caused problems in the future.

Fixes for the 'MQ CR72' dispersion model target function.

The relax_disp.plot_disp_curves user function can now handle values of NaN.

These are simply replaced by 0.0 to allow Grace to open the file.

Another bug fix for the 'MQ CR72' dispersion model.

The nu_CPMG value rather than the relaxation time was being used to calculate the R2eff values as
the division by 'n' was missing.

Fix for the 'MQ CR72' model for MQ-type data.

The check to prevent acos of a number less than 1 has been changed to switch the sign rather than to
set the back calculated R2eff to 1e99.

Converted the 'MQ CR72' dispersion model to handle MMQ data.

This model can now handle proton-heteronuclear SQ, ZQ, DQ, and MQ CPMG-type data. Some debugging
might still be required.

Bug fix for the 'MMQ 2-site' dispersion model target function.

The relaxation time was being taken as that of the first experiment for all experiments. This is a
relic from the code being copied from a single experiment type model.

The relax_disp.plot_disp_curves now shows the experiment type as part of the Y-axis label.

This is to allow for easy identification of the experiment when more than one is present.

Fixes for the relax_disp.plot_exp_curves user function for the lib.software.grace changes.