(gui) Correctly update df connection in restoreConnections()
(gui) Refactoring: rename methods related to instance refinement
(gui) New specific method to update refinement and restore connections
(gui) Refactoring

Delete saveConnections() and restoreConnections() methods.
Their content have been moved to updateRefinementAndRestoreConnections() method
(gui) Fix issue introduced in 04b51e1ed

Copy/paste is evil :rage: