another lua convenience API

libs/ardour/ardour/lua_api.h

@@ -43,6 +43,12 @@ namespace ARDOUR { namespace LuaAPI {
 	 */
 	int datatype_ctor_midi (lua_State *L);
 
+	/** Create a null processor shared pointer
+	 *
+	 * This is useful for Track:bounce() to indicate no processing.
+	 */
+	boost::shared_ptr<ARDOUR::Processor> nil_processor ();
+
 	/** create a new Lua Processor (Plugin)
 	 *
 	 * @param s Session Handle

libs/ardour/lua_api.cc

@@ -61,6 +61,12 @@ ARDOUR::LuaAPI::datatype_ctor_midi (lua_State *L)
 	return 1;
 }
 
+boost::shared_ptr<Processor>
+ARDOUR::LuaAPI::nil_processor ()
+{
+	return boost::shared_ptr<Processor> ();
+}
+
 boost::shared_ptr<Processor>
 ARDOUR::LuaAPI::new_luaproc (Session *s, const string& name)
 {