Generate guide data separately

    # Given all classes, generates namespace tree and writes it

    # in JSON form into a file.

    def write_tree

      tree = Tree.new.create(@relations.classes, @guides)

      tree = Tree.new.create(@relations.classes)

      icons = TreeIcons.new.extract_icons(tree)

      guides = Tree.new.create(@relations.classes)

      js = "Docs.classData = " + JSON.generate( tree ) + ";"

      js += "Docs.icons = " + JSON.generate( icons ) + ";"

      if @guides.length > 0

        pkg = {

          :text => 'Guides',

          :children => []

        }

        @guides.each {|g|

          pkg[:children] << {

            :text => g[:title],

            :url => "/guide/"+g[:name],

            :iconCls => "icon-guide",

            :leaf => true

          }

        }

      end

      js += "Docs.guideData = " + JSON.generate( pkg ) + ";"

      File.open(@opts.output_dir+"/output/tree.js", 'w') {|f| f.write(js) }

    end