problems if aic_Kmin =0

[DavideTisi]

if aic_Kmin=0 choosing different P* with the multiplication of Kmin_corrfactor is not possible. Moreover, the function plot_kappa_Pstar() brakes because it chooses the range of P* as 3 * self.dct.aic_Kmin e.g. line 170 of plotter.py

max_y = np.amax(self.kappa_scale * 0.5 *
                            (self.dct.tau + self.dct.tau_THEORY_std)[self.dct.aic_Kmin:3 * self.dct.aic_Kmin])