interactive integration; new user-defined fit functions reloads model list; fixed requirements.txt

src/gui_qt/fit/fitwindow.py

@@ -61,6 +61,8 @@ class QFitDialog(QtWidgets.QWidget, Ui_FitDialog):
         self.functionwidget.showFunction.connect(self.show_function_parameter)
         self.functionwidget.itemRemoved.connect(self.remove_function)
 
+        self.read_and_load_functions = self.functionwidget.read_and_load_functions
+
     @QtCore.pyqtSlot(int, int)
     def add_function(self, function_idx: int, function_id: int):
         self.show_function_parameter(function_id, function_idx)