At the Metropolitan Museum of Art we have "The Medici: Portraits and Politics: 1512 -1570" (through October 11). This is a show of Old "Masters" that tries to do the best it can for a period in Florentine art traditionally known as "Mannerism" but which the museum in its accompanying literature tries to dignify as "Renaissance." The best reason it can make this claim is that for the most part the show steers clear of the spindly, rubbery bodies and overly cluttered compositions that distinguish Mannerism's religious, mythological and allegorical paintings, focusing instead of the relatively straightforward and mannerism-free subject of portraits