Added return of None values for function calc_rotating_frame_params() if spin is not selected.
Regarding sr #3124, (https://gna.org/support/index.php?3124) - Grace graphs production for R1rho analysis with R2_eff as function of Omega_eff.
Authored by: tlinnet 2014-03-12
Parent: [r22468]
Child: [r22470]
