add alternative update table

Now after fetching updated the database is live updated and this happens stepwise. Sometime during big updates there could be some calendars be fetched and then contain some inconsistency where events where added and deleted from the database.

Fix could be creating a second table which replaces then the other one. Or we only delete and insert the changes. So that every events that is already in our events list with the same start, end, prof, room, notes, etc. then isnt updated.

1. research fetcher and get informations
2. try to fix or investigate the issue