# File lib/tf/plugins.rb, line 28
  def list pattern=nil
    # collect to lists
    _list = @plugins + @additional_plugins
    # filter by pattern if given
    _list = _list.select{|item| item.match("_#{pattern}.rb$") } unless pattern.nil?
    # get path and class name
    _list.map!{|item| [ item, file_to_class(item), pattern ] }
    # TODO: limit plugin versions (highest || use bundler)
    _list.each{|item, klass, type| require item }
    _list
  end