# File lib/backports/tools.rb, line 12
  def self.require_relative_dir(relative_dir)
    dir = File.expand_path(relative_dir, File.dirname(caller.first.split(/:\d/,2).first))
    Dir.entries(dir).
        map{|f| Regexp.last_match(1) if /^(.*)\.rb$/ =~ f}.
        compact.
        sort.
        each do |f|
          require File.expand_path(f, dir)
        end
  end