A Vintage Shorts "Short Story Month" Selection   Pulitzer Prize and National Book Award finalist Dave Eggers displays his emotional range in this quiet tour-de-force from How We Are Hungry, the often funny and masterful collection of short fiction.    After giving up responsibility, in her usual passive way, of much that has been of importance in her life--her adopted children, a condo, financial security--Rita pays for a guided hike to the summit of Mount Kilimanjaro.    An ebook Short.