Subtitles: hide {y:*} in microDVD

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>

modules/codec/subtitles/subsdec.c

@@ -973,7 +973,7 @@ static char *CreateHtmlSubtitle( int *pi_align, char *psz_subtitle )
             /* Hide {\stupidity} */
             psz_subtitle = strchr( psz_subtitle, '}' ) + 1;
         }
-        else if( psz_subtitle[0] == '{' && psz_subtitle[1] == 'Y'
+        else if( psz_subtitle[0] == '{' && ( psz_subtitle[1] == 'Y' || psz_subtitle[1] == 'y' )
                 && psz_subtitle[2] == ':' && strchr( psz_subtitle, '}' ) )
         {
             /* Hide {Y:stupidity} */