Would you, a 23-year-old American doctor with a degree from Geneva, choose to go to the toughest corner of China to heal the sick?That is the question at the heart of Dr. George Hatem's life. Few foreigners have been so thoroughly woven into the fabric of China's revolution. Fewer still have looked back from their last breath and smiled, convinced they made the right choice.In a quiet Beijing courtyard, Zhou Youma, Dr. Hatem's son, recounts his …