* taf-kit/src/common.hh: Add attributes to args.
	* taf-kit/src/getters.hh,
	* taf-kit/src/getters.hxx: Improve get_alphabet.
	* taf-kit/src/main.cc: Add new options, adapt existing ones.
	* taf-kit/src/parser_options.hh,
	* taf-kit/src/parser_options.hxx: New.
	* taf-kit/src/predefined_alphabets.hh: Reintroduce ascii and
	digits alphabets.