Implement Database support

[pehala]

We could reintroduce MongoDB support that is mostly commented out.

[pehala]

I was thinking about this and I propose this:

• We leave tracks in the separate folder
• We only save ratings and best scores

Another thing I was thinking about was if we have any reason to use only Mongo or any database will do just fine. We could use ORM and be database agnostic.

[PhilippvK]

I do not really have any opinion on this. How would you like handle credentials for a public highscore server? Or should the database be running on the same host as the server, for example inside a docker container?

If you want to implement something, feel free to do so.

[pehala]

I don't really have users figured out yet, so for this the users would as they are now, basically just unprotected nickname. So all the data would be bound to a string instead of a User object.

I suspect the DB would be separate for each server. Also to not be depending on external database, if user does not specify any database for server, we can use some file based dB like H2 or SQLite. Meaning user can still just start server and it will.work.

[pehala]

@PhilippvK I have experimented a bit with this feature and it turns out adding database support is not very lightweight and will add at least 10Mb to a size of the server. Are we in any way concerned about binary size here?

[PhilippvK]

No, I do not have anything against that increase.