The r1_fit flag is stored in the Disp_minimise_command class and passed into the target function.
This matches the details at http://thread.gmane.org/gmane.science.nmr.relax.scm/22850/focus=6736.
The specific_analyses.relax_disp.optimisation.Disp_minimise_command class calls is_r1_optimised()
and stores the result. This is then passed into the relaxation dispersion target function class.
