SAN FRANCISCO - WhatsApp is reportedly working out on three new features, including linking your account to Instagram, in order to improve its chat and notifications for its over 1.5 billion users. Apart from Linked Accounts, the two other features under development are: Vacation and Silent Mode, said WABetaInfo, a popular website that tracks WhatsApp, on Wednesday. "WhatsApp is working right now on a new feature that allows to link...