New creates a new Manager configured with the baseDir and the RetentionConfig defining how long to keep backups if labelStorage is nil, an empty manager will be initialized if retention is nil, the DefaultRetentionConfig will be used.

DefaultRetentionConfig defines a two-year retention schema with 24 hourly, 7 daily, 4 weekly and 12 monthly backups.

ErrNoBackupFound signalizes there was no backup older than the given point-in-time.

ErrNoLabelsAdded signalizes when adding an entry all possible labels were already present and the entry has not been added.