A magical-realist gem harking back to "The Purple Rose of Cairo," "Midnight" is a bit thin and glib to call a masterpiece - at 75, Allen is unlikely to have another one of those in him - but it's still a delicious trifle for anyone who has ever dreamt of bantering about the cinema with Luis Buñuel or lounging at the piano to hear Cole Porter sing "Let's Do It."Wilson, best known for playing the