dyn_spect_dataset::plot_footer

Source: dataset/dyn_spect/dyn_spect_dataset__plot_footer.pro

 dyn_spect_dataset::plot_footer
        Display a footer at the base of a plot. and return the lower
        edge of the plotting box.

 Usage:
        ybot = dsref -> plot_footer()

 History:
        Original (after rates): Aug 01; SJT
        Support flattened scaling: 20/9/01; SJT