A few fixes.   fixed fill in the blanks js, and made sure the data going into the column match answers was quoted.
Added the category page to the main menu.
Updated the question listing page to filter by category if passed a query string parameter 'c'.
Added the categories page.  Lists category, number of questions in those categories, and lets you access the question listings or quiz pages via a link.
Final of a batch of commits to add category page, and category functionality to the list and quiz pages!