Fixed the alert time calculation
Merged alert time calculation fix from 'master' into dialog
Corrected a merge failure
Cleanup of the interval dialogs
Fixed the current-alert message and did a lot of cleanup

- Fix: The current-alert message was not showing the time when the current-alert was based on a seconds interval but the (next) interval unit was set to days or weeks.
- Cleanup: Removed the 'big interval' as the functionality is currently not implemented. Renamed a lot of stuff to more resonable names.