Some .osu file sources (or database sources) may be in a bad state. We want to get these ones right as they cannot be enforced by the database itself (via FKs or constraints).
There is now a CreateContext method for retrieving a stand-alone context for threaded use.
We may want to add safety against this context being disposed (or just return a fresh one if it is).
This method allows switching between sqlite-net and EF builds without completely breaking. Note that DB migration still only happens in a forward direction, but this will allow switching back and forth without eventually being unable to start the game.