NEW YORK (Reuters) - Immigration activists clashed at the site of the World Trade Center on Wednesday when an anti-illegal immigration group called for secure borders to avoid a repeat of the September 11 attacks and counterprotesters yelled "racists go home." Members of the Minuteman Project, which patrols the U.S.-Mexican border for illegal immigrants, pushed and shoved members of an immigrant rights group that showed up at the event. Jim Gilchrist and Jerome Corsi, authors of "Minutemen: The Battle to Secure America's Borders," were whisked away when some immigrant rights supporters broke through a police barrier and scuffled with Minutemen...