Fix filter settings in the configuration dialog

- Changed filter settings were not synchronized between widgets, settings objects
- StopListWidget, StopWidget and StopSettingsDialog now take a pointer to the
list of filter settings. That way changes are synchronized automatically with
these widgets.
- The other problem comes with the "affected stops" widgets. Changes need to be
stored in the synchronized filter settings object directly, because otherwise
eg. a StopSettingsDialog with old filter settings could be opened from the
stop list widget.
- Remove all filter name translations and associated methods
(deprecated, there's no "Default" filter configuration any longer)