“The Last Airbender” is the live-action feature film based on the highly successful animated series on Nickelodeon. It’s also the center of a growing controversy about casting and race. The series features Asian settings, costumes, architecture, and character and location names that incorporate Chinese, Japanese and Southeast Asian phonemes — such as “Aang,” “Fong” and “Sing.” And yet, when casting the motion picture, the studio chose four white actors to play the leads. When one of the actors dropped out, he was replaced by Dev Patel of “Slumdog Millionaire” fame, but it’s still the case that three of the four leading actors are white.