code: def trip_name_to_directory_name(name):
      
      out = name.lower()
      out = re.sub('[:/\ ]', '-', out)
      out = re.sub('[.,]', '', out)
      out = re.sub('--+', '-', out)
      out = out[:30]
      return out
docs: Convert a name like "Mt. Tam: Ridgecrest Blvd to Alpine Lake via..." to
      something like "mt-tam-ridgecrest-blvd-to-alpi".