* taf-kit/src/main.cc: Add a call to check_collision.
	* taf-kit/src/parser_options.hh: ,
	* taf-kit/src/parser_options.hxx: Add check_collision function to
	  check if a token representation intersect the alphabet.
	* taf-kit/tests/vcsn-char-b.test: Add some tests for the previous
	  function.