MEDAN, Indonesia, Sept 5 (Reuters) - At least 100 people are feared dead after a Boeing 737-200 crashed in the centre of Indonesia's third biggest city on Monday just after takeoff, breaking into pieces and setting fire to homes and cars. The plane, operated by local carrier Mandala Airlines, had 112 passengers and five crew on board, said Asril Tanjung, the airline's director. The cause of the crash in Medan city was being investigated, but foul play was highly unlikely, he said. The plane slammed into the heart of Medan, the capital of North Sumatra province, sparking widespread panic, witnesses...