The high level object must at least live as long as the input_resource,
I used playlist, vlm or libvlc_media_player.
 It avoids invalid reparent of the vout, aout and sout on input changes.

 It breaks support for per input options used for creating vout, aout
and sout (:sout= is not impacted). I will fix the vout case.

 It breaks invalid usages of vlc_object_find(INPUT, PARENT) used
at least by :
 - the sout modules describe and display.
 - the sout statistics.
 - the vout splitter change
 - the snapshot vout display.
I will fix the vout related ones.