add Source::clear_cue_markers()

libs/ardour/ardour/source.h

@@ -115,6 +115,7 @@ public:
 	CueMarkers const & cue_markers() const { return _cue_markers; }
 	void add_cue_marker (CueMarker const &);
 	void remove_cue_marker (CueMarker const &);
+	void clear_cue_markers ();
 	PBD::Signal0<void> CueMarkersChanged;
 
 	virtual samplepos_t natural_position() const { return _natural_position; }

libs/ardour/source.cc

@@ -396,3 +396,9 @@ Source::remove_cue_marker (CueMarker const & cm)
 	}
 }
 
+void
+Source::clear_cue_markers ()
+{
+	_cue_markers.clear();
+	CueMarkersChanged(); /* EMIT SIGNAL */
+}