bluray: fix displaying of still images

MPEG-TS demuxer does not flush last video frame if size of PES packet is unknown.
Packet is flushed only when TS packet with PUSI flag set is received.
Fix this by emitting (video) ts packet with PUSI flag set.
Add video sequence end code to payload so that also video decoder is flushed.
Set PES packet size in the payload so that it will be sent to decoder immediately.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
bluray: cache current playlist info.

Avoid reading playlist info from disc every time it is used (adding streams, selecting streams, changing clip, ...)

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
bluray: improve readability by using local variables

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>