Musical jelly beans are scattered all over Broadway. If well done, these shows are colorful and fun to eat. They taste good going down, give you a temporary high but ultimately are empty calories. They leave you with nothing. Then there’s the current revival of Stephen Sondheim’s Follies. You might not be able to hum all its songs as you exit the theatre, but you’ll surely be thinking Sondheim, feeling Sondheim. And for many days to come you’ll be reflecting on all he has to say about human follies, relationships and, depending on your age, your own life choices