Fix issues related to hiding beatmaps
Make ProgressNotification's status and progress thread-safe
Fix issues with deletion
Main fix is avoiding nullrefs being thrown when metadata isn't present on a beatmap (quite a common scenario).
Because we are not sharing a single context, we need to use Update to attach the entity to the local context.
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
Quite regularly a task will hold a reference to a progress notification and udpate it as progress is made. Therefore these operations should be thread-safe.