By Harold Isaac PORT-AU-PRINCE (Reuters) – Hundreds of Haitian children are taking refuge at a prestigious high school in Port-au-Prince after escaping gang violence in the town of Cite Soleil that killed some 400 people and destroyed hundreds of homes this month. At the sprawling campus of Institution Saint-Louis de Gonzague, which is currently empty for summer vacation, children ranging from teenagers to toddlers are sleeping in classrooms that are serving as improvised dormitories. They chatted and joked in the recess yard on Friday, playing hide and seek or improvised soccer games with pla…