Tell users what's wrong when using a study tool before entering information

[tddawson]

If you go to a matching game, flashcards, or multiple choice test without any valid questions/cards/facts, it's not a great sight.

• If they have entered nutrition data but filtered the tool so that they're not shown, display a message about changing the filters.
• If they don't have any nutrition data stored, tell them to fill it out on the nutrient table page. For prototype purposes, we could have a button that lets them load our sample data.

[tddawson]

Closed as mostly fixed; will switch so they automatically load full data instead of empty data.