Well, let’s just dip our toe shoes into the water, here, and see if there’s any balletomania afoot, for a new meetup now. Amid the epoch of “Black Swan" at the movies, and with the Giants having won the World Series (yes, whipping through 32 fouetté turns is almost as hard as hitting a Lincecum fastball), and now the first book ever published about the entire history of ballet (“Apollo’s Angels,” by Jennifer Homans), and, ta-dah, most important of all, with the world-class San Francisco Ballet …