MOSCOW (Reuters) - The mystery surrounding a missing merchant ship deepened Thursday with the vessel's operator suggesting piracy and maritime experts suspecting foul play or even a secret cargo. The Kremlin ordered Russian warships to join the hunt for the 4,000-tonne, 98-meter bulk carrier Arctic Sea, whose fate has baffled maritime authorities across Europe and North Africa. The Maltese-registered vessel, carrying a $1.3-million cargo of timber, was supposed to have docked on August 4 in the Algerian port of Bejaia. It never arrived and is thought to have last made contact from the Atlantic Ocean off the coast of France....