Eliminated the abstract class Value, as it is not currently adding anything useful.
Simplified the Quiz finder methods to only return Option[QuizItemViewWithChoices], not a pair
Trimmed down QuizGroupWithHeader and stopped using it in the Quiz finder functions.
Further trimming.
Allow the memory level index inside the memory level entity.
Initial implementation of the ProduceQuizItem typeclass.
Made the Quiz entity a member of the ProduceQuizItem typeclass.
Refactoring: moved typeclasses into their own packages under model.action
Moved ProduceQuizItem tests into their own new class.
Tiny refactoring: use copy method.
Subclassed the ProduceQuizItem typeclass for the normal case of no extra parameters needed.
Moved around some method parameters for consistency.
Eliminated redundant parameter for constructWrongChoices().
Moved parameters around for consistency again.
Made similarityPredicate a parameter of constructWrongChoicesSimilar, for consistency with QuizGroupMemoryLevel.
small cleanup around similarityPredicate
Moved code into the new ConstructWrongChoices typeclass.
Moved tests for ConstructWrongChoices into the new ConstructWrongChoicesSpec class.
Updated build to 0.972.