Sundance’s showcase of classic sitcoms continues, with today’s daytime launch of a mini-marathon of one of the shows that changed the face of television: 1970’s The Mary Tyler Moore Show, the first series from the taste-establishing, groundbreaking MTM Productions. The first half of Season 1 is shown in a big burst starting at 6 a.m. ET, with more episodes to follow. It takes attitude, and a little bravery, for Sundance to clear so much time on its schedule for such a quality, yet vintage, series. Sundance has got spunk. And, in this case, I like spunk…