upnp_intel: fix a potential crash, and add some more debug output

* Do not poke the screensaver is the stream is paused (idea from Adam Dane)
* Poke the screensaver every 30s as told in the comments (fix from Adam Dane)

Motion control interface can now be used with the rotate video filter. (Should be usefull when watching videos on a boat i guess ... :) ) Command line: vlc --control motion --motion-use-rotate --video-filter rotate <the video>

This still needs work to make it look better, and be able to use it with the "motion" control module.

Correctly count the children of a node. The previous code counted the endpoints too, which gave a too high children count.

(needs backporting)

Don't use dl_open on win32
Both patches by Tim Schuerewege. thanks.

* modules/gui/qt4/qt4.cpp: lower the priority of the QT4 dialogs provider so the skins interface is usable again.

Fix MacOS X black screens and play as background options. These are 'window level' options and as such should not use p_real_vout, because that's just for options shared by the opengl and the quickdraw renderer