This seems to be the latest fashion in poland, for {y:i} (italic) and
{y:b} (bold), but I don't know how to correctly support it:
 - should we remove the tags in the demuxer like the MPL2 one (bad
   solution for MPL2 too)?
 - should we replace it by <i> in codecs?
(cherry picked from commit 195b652da5facd60397504f706a44d97bd70eb90)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>