All processables are now created with an instance of Configuration, and they use that instance's settings.
Added Configuration.CreateEphemeralCopy() to clone Configuration without persistence.
- Remove instance queue. This is a database, after all, and is designed to be accessed and written to concurrently
- Reduce the number of calls to DbContexts.Create()
- Ensure that no LibationContext remains open across an await boundary. Multithread context access is the most likely culprit for past issues.
- Make all Update UserDefinedItem methods asynchronous.
- Configuration.LibationSettingsAreValid is true if Books property exists and is any non-null, non-empty string.
- If LibationSettingsAreValid is false, Libation will prompt user to set up Libation.
- When the main window is shown, Libation checks if the books directory exists, and if it doesn't, user is notified and prompted to change their setting
- When a user tries to liberate or convert a book, Books directory is validated and user notified if it does not exist.
