[MPlayer-dev-eng] NUT cleanup

[Rich Felker]

An additional topic: after talking on #mplayerdev today, several of us
realized that the current interleaving requirement is rather stupid.
Right now it says that pts must be monotone for packets with pts==dts.
A much cleaner requirement would be that dts be monotone for all
packets (across all streams). This is also a slightly stricter
condition in the presence of high decode_delay, meaning that it makes
error detection from bad pts slightly more robust.

Rich