Mark Rye was a gentle soul and a voracious reader. But his alcohol addiction might have led to his death as he lay outside on a night when temperatures plunged to the low 20s.An autopsy revealed no obvious cause of death for Rye, a transient found dead in his sleeping bag outside a Grass Valley business Monday morning.Toxicology reports have been ordered, but they can take four to 10 weeks, said Nevada County Coroner Paul Schmidt.Rye was found dead in an alcove of a building in the 2000 block of Nevada City Highway with a sleeping bag over him. Empty …