What would compel a young woman to walk almost 1,700 miles across the Australian Outback, with only a dog and a quartet of camels for company? As real-life nomad Robyn Davidson (played by Mia Wasikowska) says at the start of "Tracks" — director John Curran's handsome biopic — "I believe that when you've been stuck too long in one spot, it's best to throw a grenade where you are standing and jump, and pray."