Print require/load tree

ruby_require_load_tree.rb

  $require_level = []
  alias :orig_require :require
  def require(file)
    puts "#{$require_level.join}#{file}"
    $require_level << "-"
    r = orig_require(file)
    $require_level.pop
    r
  end

  alias :orig_load :load
  def load(file)
    puts "#{$require_level.join}#{file}"
    $require_level << "-"
    r = orig_load(file)
    $require_level.pop
    r
  end