first commit making the persistence plot
actually committing some files (added from wrong spot)
persistence plot ready to start integrating
Merge remote-tracking branch 'remotes/pyrf/master' into persistence_plot

Conflicts:
	pyrf/gui/plot_widget.py
minor cleanup
fix persistence example #! and Qt import
Merge remote-tracking branch 'remotes/pyrf/master' into persistence_plot

Conflicts:
	pyrf/gui/plot_widget.py
Merge wardi's quick fixes in
Merge remote-tracking branch 'remotes/pyrf/master' into persistence_plot
first try to add persistence to rtsa
missing setYRange call
fix persistence plot
add persistence gradient editor
exponential>linear
scale freq axis
fix playback of old recordings
properly display persistence plot in rtsa
Merge remote-tracking branch 'wardi/fix-old-recording-playback' into persistence_plot
Merge remote-tracking branch 'wardi/persistence_plot' into persistence_plot
Merge remote-tracking branch 'pyrf/master' into persistence_plot