Warn when invalid guide name is used.

    def load_guide(guide)

      return Logger.warn(:guide, "Guide not found", guide["url"]) unless File.exists?(guide["url"])

      return Logger.warn(:guide, "Guide not found", guide[:filename]) unless File.exists?(guide[:filename])

      unless js_ident?(guide["name"])

        # Guide name is also used as JSONP callback method name.

        return Logger.warn(:guide, "Guide name is not valid JS identifier: #{guide["name"]}", guide[:filename])

      end

      begin

        return format_guide(guide)

      end

    end

    # True when string is valid JavaScript identifier

    def js_ident?(str)

      /\A[$\w]+\z/ =~ str

    end

    # Ensures the guide dir contains icon.png.

    # When there isn't looks for icon-lg.png and renames it to icon.png.

    # When neither exists, copies over default icon.