Implement a initial setup/help wizard

[remuslazar]

Some app features are not very discoverable, especially for new users after first install. E.g. the existence of the app settings page itself but also the need of setting up the filter settings there initially, so the app shows the result set the user does expect in the first place, a kind-of "help" page or a tutorial/setup wizard should be implemented, leading new users through the setup process and also explaining some of the app features (e.g. what the map center icon means, how the reload works etc.)

Relates #1, #2