Calendar Customization

[kordianbruck]

Sync from/to Android: TUM-Dev/Campus-Android#410

[nerdsupremacist]

Oh dang! We're finally generating content.

Looks like I will finally have to include SQLite in this project, if we're doing two way syncing.
Most people go with: https://github.com/stephencelis/SQLite.swift

We'll see how easy it is to use or evaluate others.
I would add this to a 1.5 release though. Because if we're finally adding a fully fledged DB, we might as well transfer our caching layer over there...
Instead of the file cache we have right now

[kordianbruck]

DB does not replace you caching hopefully ;-)

[nerdsupremacist]

It doesn't have to. But I already had to get pretty clever/hacky to solve the Newsfeeds caching without a database...

Now that it's worth it to include a database, perhaps we can get rid of stuff like this:
https://github.com/TCA-Team/iOS/blob/2acc72ab33b49c4c158ad58b7859af29e4ef77a8/TUM%20Campus%20App/NewsManager.swift#L40