2sxc 08.04.03 with various fixes and minor improvements

Full list here https://github.com/2sic/2sxc/issues?q=is%3Aissue+milestone%3A%222sxc+08.04.03+Hotfixes%22+is%3Aclosed

Most important

1. Apps can now load with ajax as well - if they want to :)
2. AJAX loading on a details page is now supported
3. multiple file libraries per edit-dialog now don't throw an error
4. field groups (titles) can now be collapsed by default
5. minor bugs with alerts, cancel-edit etc.
6. Minor change to the way inner content-items are included (was important for good architecture) - this should't affect anybody yet
7. fix module data source not working in the visual query because context information was missing