Coming-of-age comedies about young protagonists with esoteric dreams are not exactly a rarity. What is less common, though, are films as spirited and charming as Nida Manzoor's “Polite Society,” a roundhouse kick of a movie about two British-Pakistani sisters that marries Jane Austen with kung-fu flare. “Polite Society,” the feature film debut of writer-director Manzoor, creator of the British sitcom “We Are Lady Parts,” is a fun and increasingly preposterous comedy.