Moved PD_plot_pmtm to PD_color_band_plot_pmtm in anticipation of writing a new script to do spectral boundedline plots; editing (not yet debugged) in PD_powerfreq & PD_powerfreq_v2; debugged edited versions of PD_spectrogram & basic_HT_improved_x11; added median & mean power per minute to PD_stats_pmtm.