This also gets rid of one user of setjmp(), but it is still found in
the (stupid?) PNG codec and OS X interfaces.

...and VLC does not quite work on Linux 2.2 anymore.

As it doesn't seem to be called after creating playlist in core on startup
and playlist-model calls rebuild on creation anyway.

Also remove item-current from playlist-model which ain't used.

for future generations

This allow a little bit more flexibility and won't require the same level of code quality in configure tests (is that a plus?).

This try to avoid vlc_object_find() as much as possible.
This is conservative, because where there is no associated parent input, we'll try to find in certain cases the parent input. This will probably be
 removed later on. Because yes, there is not necessarily a parent input for access and demux, especially if created from stream_UrlNew().

Reported by Andy Chenee.

This reverts commit 8c243091.

Not sure how thread-safety works here though.

This reverts commit 3c55f6d8.

This is dead code (which does generate a warning!!!)

This reverts commit 3d82d569.

This reverts commit 908d0b93.

Spotted by a warning.

The playlist needs to be fixed here not to use signed for its size, but...