A look at some noteworthy television this week: Art in the Twenty-First Century (Sunday, 10:00 p.m., WNET 13) Four artists - Robert Adams, Mark Dion , Iñigo Manglano-Ovalle Ursula von Rydingsvard – who explore the intersection between nature and culture. Billy Crystal: The Mark Twain Prize (Monday & Thursday, 9:00 p.m., WNET 13; Saturday, 7:30 p.m. WLIW 21) Billy Crystal receives the tenth annual Mark Twain Prize for American Humor at the Kennedy Center in... more ›