By Ulf Laessing OUTSIDE EL FASHER, Sudan (Reuters) - About 300,000 people have fled their homes due to a surge in fighting in Sudan's Darfur region this year and are now living in terrible conditions and short of food, the United Nations aid chief said on Wednesday. The figure is higher than the combined number of displaced people for the past three years. Violence is down from a peak in 2004-2005 but fighting between the army, rebels and rival tribes has increased significantly since January. "Here in the hot sun in summer they've got almost nothing. They still have to walk for water," U.N. ...