We shouldn't look for the playlist from the vout too... but...

Export update_GetRelease() to the plugins
Modify qt4 & wx GUIs to reflect this change

This fixes a crash on Mac OS X.

This leaves us more room to rework the macros later on

Fix 0448c670 as I forgot to use pl_Yield instead of vlc_object_find.
And fix some other use of vlc_object_find for the playlist.