SPECIAL PREMIERE: There’s only really one truly delightful new offering on TV tonight – but it’s one that covers the entire history of television, and salutes an actress who has been there from the start, and never left. The subject of tonight’s PBS biography is Betty White, whose career includes the sitcoms Life with Elizabeth in the early 1950s (pictured) and Hot in Cleveland some 60 years later – and, in between, makes room for everything from regular roles on The Mary Tyler Moore Show and The Golden Girls to memorable guest spots on St. Elsewhere and Boston Legal. Oh, and you can’t forget her times as a panelist on Password. At least I can’t. For a full review, see David Hinckley’s All Along the Watchtower. Check local listings.