In winter, it’s all about the skiing, and Jackson’s extreme terrain, chutes and fearsome reputation have long attracted expert thrill-seekers and film crews. This year, Jackson shows off its softer side after a three-year, $5 million ­investment in new, groomed beginner and intermediate terrain. In Casper Bowl, a new lift, tree removal and grading have created a contained paradise of blue cruisers with just a three-and-a-half-minute, high-speed chair ride. Hence the resort’s kinder, gentler official motto for this winter: “All Blue, All New.”