Merge commit '8a9e7d2980c17afe07c8c784f035b7d75478781f' into persistence_plot
show/hide persistence palette too
disabled all mouse functions on the persistence plot
persistence fades to black, persistence resets when the device is retuned
fixed case of no data being passed to waterfall
changed preset waterfall color
add_row won't do anything if no data is passed
removed unused variables
changed name of waterfall to spectrogram
Merge pull request #1 from mfarhan12/persistence_plot

Persistence plot adjustments
Merge remote-tracking branch 'pyrf/master' into persistence_plot

Conflicts:
	pyrf/gui/plot_widget.py
Merge remote-tracking branch 'remotes/wardi/persistence_plot' into persistence_plot

Conflicts:
	pyrf/gui/persistence_plot_widget.py
	pyrf/gui/plot_widget.py