MKV: parse more metadata

modules/demux/mkv/matroska_segment.cpp

@@ -238,6 +238,8 @@ static const struct {
                      {vlc_meta_Description, "DESCRIPTION"},
                      {vlc_meta_Publisher,   "PUBLISHER"},
                      {vlc_meta_URL,         "URL"},
+                     {vlc_meta_TrackNumber, "PART_NUMBER"},
+                     {vlc_meta_Date,        "DATE_RELEASE"},
                      {vlc_meta_Title,       NULL},
 };