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.

We end up looking up from p_libvlc anyway, so we might as well as well
do it from the beginning

Pointed out by Hannes Domani

Actually, we just need to do like Direct3D: catch left-click.

lamers