class String
  def to_normal
    # String.tr() no funciona con caracteres de mas de 1 byte
    d = self.downcase
    accents = {
      'á'=>'a',
      'é'=>'e',
      'í'=>'i',
      'ó'=>'o',
      'ú'=>'u',
      'à'=>'a',
      'è'=>'e',
      'ì'=>'i',
      'ò'=>'o',
      'ù'=>'u',
      'ñ'=>'n',
      'ä'=>'a',
      'ë'=>'e',
      'ï'=>'i',
      'ö'=>'o',
      'ü'=>'u',
      '¿'=>''
    }
    accents.each do |accent,rep|
      d.gsub!(accent,rep)
    end
  	d.gsub(/\W+/, ' ').strip.gsub(/\ +/, '_')
  end
end