Fix display of parenthesis in arabic

Fix display of parenthesis in arabic

Actually the workaround that is used to show parenthesis in the right direction
is not needed any more, since this is part of the unicode bidi writing algorithm.

This fixes at the same time the use of [] or  as delimiters in arabic, which was wrong on screen.

Note that there is a problem with hebrew, but this will require a fileformat change.