update to changes from mlz repo

- bug fixes in error.py
- add from * to raise statements
- fix py35 compatibility
- finalize omit_unchanged_within feature
- fix follwup bug (missing Param.override) in proxy.py

Change-Id: I621c01a0d5e1ec6696fb06f39666f3316fb53649

secop/gui/cfg_editor/node_display.py

@@ -26,7 +26,7 @@ from secop.gui.qt import QHBoxLayout, QSizePolicy, QSpacerItem, Qt, QWidget
 
 class NodeDisplay(QWidget):
     def __init__(self, file_path=None, parent=None):
-        QWidget.__init__(self, parent)
+        super().__init__(parent)
         loadUi(self, 'node_display.ui')
         self.saved = bool(file_path)
         self.created = self.tree_widget.set_file(file_path)