The relaxation dispersion calculate user function now stores the back calculated R2eff values.
A number of changes were required for this. The code from the end of the Disp_result_command.run()
method was converted to the function specific_analyses.relax_disp.disp_data.pack_back_calc_r2eff().
This allows the back calculation R2eff unpacking code to be shared. The new has_proton_mmq_cpmg()
function has also been created to simplify the code.
