This adds trailing lines to files,
removes trailing white space in all the other lines and unifies line endings.
Additionally it formats the test code with `black`.
The scheduler now will react to a new fixed time also if 24h haven't passed yet.
All in all the code is supposed to be cleaner and easier understandable.
The logging was slightly modified.
Scheduler now has the ability to run jobs on multiple repositories concurrently and run multiple jobs on one repo (by queuing them).
For each repository, there is one queue. I have represented a queue by a 'site'. Between sites (ie repository), tasks run concurrently. On one site, tasks run one by one. The user also run tasks by adding them to the queue but he can't run multiple backups because start backup button is disabled when a job is running.
* Simplify non-blocking BorgThread.run.
* Fix issue with displaying nested folders in extract-dialog.
* Fix error text expansion.
* Add many new tests. Dont open main window on startup.
