Remove unused QuizHelper::getAllTitles().
node_save($quiz) => entity_save('quiz_entity', $quiz);
Misc on QuizHelper::setQuestions().
Clean up QuizHelper::getQuizzesByUserId($uid).
Move getQuizzesByUserId() from QuizHelper to Stats class.
Format code in quiz_stats.admin.inc
Move countAlwaysQuestions() from QuizHelper to Stats.
Move QuizHelper::countQuestion() to Stats::countAllQuestions().
Add Stats::countRandomQuestions().
Fix wrong column name in _quiz_get_attempt_count().
misc
Remove unsed QuizHelper::getScoreData().
Rename mis understood properties of response object.
Move saveQuestionResult() from QuizHelper to result controller -> writer.
Move copyQuestions() from QuizHelper to NodeInsertHelper class.