Recent Italian politics have been chaotic and outrageous - so what else is new? As can be seen in the terrific period films in the Harvard Film Archive's series Viva L'italia! The Risorgimento On Screen, that's pretty much the way it's always been. The program opens with Luchino Visconti's masterpiece, Senso (1954; 7 pm), a lushly romantic extravaganza set during the 19th century Italian war for independence in which a patriotic Venetian countess falls in love with an officer of the occupying Austrian army.