more result options

this patch aims to do 3 things:

1. if you choose not to use it, it should not affect any already-created quizzes.

2. you can specify result ranges, like 0-49, 50-90, 91-100, and then give the user feedback based on the range their score falls into at the end of the quiz. Note that this requires the quiz to be a scored quiz, meaning the pass rate is greater than 0. Also note that this has absolutely no effect on passing the quiz.

3. for an unscored quiz (pass rate is 0), you can set up result categories (like 'cat person' and 'dog person'). Unlike a scored quiz, these categories aren't ranked, so one is not better than the other, and they don't use ranges. Each answer must then be linked to a particular category. At the end of the quiz, the user is given feedback based on which category contained the majority of their answers. (so if the majority of their answers were linked to the 'cat person' category, you could give feedback like "you really like cats, huh?").

This third option requires manage questions workflow patch, to create the proper link between quizzes and questions.

I'd appreciate any comments on how to improve this patch, and any problems found within it.