def add_link l
            l.door = @iotas[l.src]
            raise Edoors::Exception.new "Link source #{l.src} does not exist in #{path}" if l.door.nil?
            (@links[l.src] ||= [])<< l
        end
def add_link l
            l.door = @iotas[l.src]
            raise Edoors::Exception.new "Link source #{l.src} does not exist in #{path}" if l.door.nil?
            (@links[l.src] ||= [])<< l
        end
adds the given Link to this Room

 @param [Link] l the Link to add

 @raise Edoors::Exception if the link source can't be found in this Room