Death Row inmate Richard Allen Davis, who kidnapped and murdered 12-year-old Polly Klaas in Petaluma in 1993, was found unconscious in his San Quentin Prison cell Sunday night and rushed to the hospital, authorities said today. Davis, whose crime is largely responsible for California's three strikes law, overdosed on opiates, according to prison spokesman Vernell Crittendon. It was not clear Monday whether it was a suicide attempt or an accidental overdose. The drugs are believed to have been obtained from an outside source, probably during visiting hours, Crittendon said. Prisoners, he said, "are still allowed to visit with their loved...