fix #75 : display a message when saving or loading a file failed

[alixdamman]

No description provided.

[gdementen]

Wouldn't it be better to merge both code paths and inline _update_arrays?

if isinstance(filepath, (list, tuple)):
    filepath = None
    names = filepath
    ...
    current_file_name = dirname
    display_name = ' ,'.join(basenames)
else:
    names = None
    current_file_name = filepath
    display_name = filepath
try:
    session.load(filepath, names)
    self._reset()
    self.set_current_file(current_file_name)
    self._add_arrays(session)
    self._listwidget.setCurrentRow(0)
    self.unsaved_modifications = False
    self.statusBar().showMessage("Loaded: {}".format(display_name, 4000))
except Exception as e:
    QMessageBox.critical(self, "Error", "Something went wrong when loading: {}\n{}".format(display_name, e))

[gdementen]

needs a changelog