There's now a BackupManager class, which handles all backup
management functionalities ProfileManager used to have.
ProfileManager also got adapted to paths being available from
Configuration, which was long overdue.
Application was adapted to the various changes.
Partial revert of 04d2ab9dc7.
I forgot about the Backup struct when I was working on the backup
manager, and was about to run into a conflict sooner or later.
