Change PD options to be a tuple of dictionaries.

Change PD options to be a tuple of dictionaries.

Each option consists of a dictionary with the following keys:

  id      The option id, which is passed in when setting a value.
  desc    A description of the option, suitable for display.
  def     The default value for this option.
  values  (optional) If present, a tuple containing values the option
          may take. They must be of the same type as the default.

Valid types for the options are UTF-8-encoded strings, integers, and
floating point values.