option to ignore feedback detection - /i know what i'm doing/ mode.

This currently only has effect if the loop connection is
made/unmade while the option was set/unset.
Toggling the option itself won't trigger a graph re-order

gtk2_ardour/rc_option_editor.cc

@@ -1512,6 +1512,14 @@ RCOptionEditor::RCOptionEditor ()
 
 	add_option (_("Audio"), oac);
 
+	add_option (_("Audio"),
+		    new BoolOption (
+			    "ignore-feedback-loops",
+			    _("Ignore Feedback Loops"),
+			    sigc::mem_fun (*_rc_config, &RCConfiguration::get_ignore_feedback_loops),
+			    sigc::mem_fun (*_rc_config, &RCConfiguration::set_ignore_feedback_loops)
+			    ));
+
 	add_option (_("Audio"), new OptionEditorHeading (_("Denormals")));
 
 	add_option (_("Audio"),

libs/ardour/ardour/rc_configuration_vars.h

@@ -192,6 +192,7 @@ CONFIG_VARIABLE (bool, sound_midi_notes, "sound-midi-notes", false)
 CONFIG_VARIABLE (bool, use_plugin_own_gui, "use-plugin-own-gui", true)
 CONFIG_VARIABLE (uint32_t, max_recent_sessions, "max-recent-sessions", 10)
 CONFIG_VARIABLE (double, automation_thinning_factor, "automation-thinning-factor", 20.0)
+CONFIG_VARIABLE (bool, ignore_feedback_loops, "ignore-feedback-loops", false)
 
 /* denormal management */
 

libs/ardour/session.cc

@@ -1522,7 +1522,7 @@ Session::resort_routes_using (boost::shared_ptr<RouteList> r)
 	/* Attempt a topological sort of the route graph */
 	boost::shared_ptr<RouteList> sorted_routes = topological_sort (r, edges);
 	
-	if (sorted_routes) {
+	if (Config->get_ignore_feedback_loops() || sorted_routes) {
 		/* We got a satisfactory topological sort, so there is no feedback;
 		   use this new graph.
 
@@ -1553,8 +1553,9 @@ Session::resort_routes_using (boost::shared_ptr<RouteList> r)
 #endif
 
 		SuccessfulGraphSort (); /* EMIT SIGNAL */
+	}
 
-	} else {
+	if (!sorted_routes)  {
 		/* The topological sort failed, so we have a problem.  Tell everyone
 		   and stick to the old graph; this will continue to be processed, so
 		   until the feedback is fixed, what is played back will not quite