log support for viz.waterfall()

[ahmadtourei]

It would be great to have the ability to plot the logarithm of amplitudes in patch.viz.waterfall(), similar to the functionality in patch.viz.spectrogram(log=True). For example, to plot the log(amplitude) of a spectrum:

pa_freq = pa.dft("time")
pa_freq_plot = pa_freq.abs().viz.waterfall(show=True, log=True)

I may be able to work on it in a few days.

[ahmadtourei]

It is implemented in #392.