Implement SQLite

[pixup1]

Implement SQLite database.

Managed games servers are now stored in the database.

[Ecnama]

Besides from that I'm wondering if we should keep the "connection" (file handle) to the database file open. When writing a lot of data (e.g. damage events) into the database it might be better to not open and close the file over and over again. What do you think?

You're right, we should never have a transaction conflict problem with the database, so it's not necessary to open a new connection for each data manipulation.

[pixup1]

We will make a new PR when we finish everything with our fork (eventually)