App should return list of pioneer_dea objects

[ohjakobsen]

The app supports returning one or several models when the user clicks the quit button within the app. As of now, this is a custom list created within the app. With the advent of the new S3 classes, the app should return relevant objects based on these classes. This might require some rework of the internal logic in the app, as we currently are not using the high level compute_dea() function to create model objects.