Here’s a cat story that won’t make you groan. First of all, Rupert, in Jules Feiffer’s latest book for children, “Rupert Can Dance” (Michael di Capua, $17.95), isn’t what you’d call cute, more like an orange Yoda on all fours. And he doesn’t just lie around, he’s got a passion for strutting and prancing while his owner, little Mandy, sleeps. He even uses her dancing shoes.