CHICAGO --Keeping young people safe this summer is the aim of an expended program announced Wednesday by Mayor Richard M. Daley and other officials.The mayor went to Humboldt Park to point out that 280,000 youngsters are expected to participate. That's 5,000 more than last year. The activities will include day camp, sports, library reading, internships, artistic programs and expanded summer school courses, including bi0-lingual classes. "Providing these activities is more important this summer than ever before. Our city is really outraged by the number of violence, of young people shooting young people," Daley said. "Our schools are safe. Our schools are safe havens. So what we'd like to do is to have them engaged more in our schools, as much as we can," said Rufus Williams, school board president.