Fix bug #12: Balanced square brackets test should recognize multi-line [Illustration] tags
1 **************** INPUT ****************
2 Katherine was assailed by a sudden doubt. Had she mailed that letter? Yes,␊she was certain of that. She had run out to the mail box at ten o'clock
3 at night especially to mail it. What had gone wrong? Why wasn't there␊someone to meet her?
4 **************** EXPECTED ****************
6 Katherine was assailed by a sudden doubt. Had she mailed that letter? Yes,
9 at night especially to mail it. What had gone wrong? Why wasn't there