Playout & Fallback Logic

In case some schedule cannot be played for some reason, there are 3 types of fallback/emergency scenarios:

1. Schedule Fallback: Another programmed playlist for some empty timeslot is played (#44 (closed))
2. Show Fallback: Another programmed playlist for this show is aired (#44 (closed))
3. Station Fallback: A playlist or folder with random music for this show is aired (#43 (closed))

Each playlist can consist of audio file entry. They can be played in linear order or randomly (compare Random Music feature). In case of a playlist consisting of live or stream contents, it is expected that there is a recording of such show available. In such scenario the recorded version is played back only. (Update: It turned out, that playlists can always change there contents by design, see comment #3 (comment 1637))

In case a fallback is triggered, following should happen:

1. Notify PM/PK about the incident via email (#38 (closed))
2. Include info on the fallback type and if the timeslot was empty (no schedule programmed) (#38 (closed))
3. (Optionally) Notify even before the actual broadcast has happened (this is scheduled for a later AURA release as it's optional)