def new_files
      files = Set.new
      site.each_site_file { |item| files << item.destination(site.dest) }
      files
    end
def new_files
      files = Set.new
      site.each_site_file { |item| files << item.destination(site.dest) }
      files
    end
Private: The list of files to be created when site is built.

 Returns a Set with the file paths