Add HDMV menu support to stream_bluray, activated by opening with
"bd://menu/..." or the global --disc-menu option.
The IG overlay plane arrives through the libbluray YUV overlay
callback. Decode the palettized RLE into a BGRA plane (premultiplied
alpha) and hand it to the player via STREAM_CTRL_GET_NAV_OVERLAY.
STREAM_CTRL_NAV_CMD maps arrow/select/menu/popup/mouse actions onto
bd_user_input() and bd_mouse_select(). Events relevant to the menu
state (title, playlist, menu on/off) are tracked so
STREAM_CTRL_GET_NAV_STATE can report an active menu, and playlist
changes bump discontinuity_id so the player flushes stale packets.
Kacper Michajłow
3a8b6995e9