Fix issues with deletion
Main fix is avoiding nullrefs being thrown when metadata isn't present on a beatmap (quite a common scenario).
Use EF for SQLite interfacing
Remove duplicate reference to opentk package
Nuke it all.
Bonus stage
A factory is supposed to be re-used.
Also hard-disables it for uninteresting log levels, providing a further performance boost.
Simplify gradient usage in Letterbox Overlay