r9296:9299 changes

Make sure the wxWindows development headers and libraries are present when skins2 module is enabled. Without wxWindows the skins2 interface is not very usable.

* modules/audio_output/portaudio.c: channel reordering patch by Frederic Ruget + slightly simplified by me.

 * support incorrect announces that does not include parameters we don't
   parse anyway, change the corresponding msesage from Warn to Dbg.
 * convert UDP to udp, to get the right icon in the playlist
 * fixed a potential crash given away by gcc's warnings

* modules/video_output/directx: in embedded mode, we now use the current monitor when switching to fullscreen.

* Fix playlist release bug
* Add sdp and rtp as network type items

* modules/video_output/directx: last attempt at fixing the spurious taskbar item after switching to fullscreen (it actually also simplifies the code a bit as well).

* modules/audio_output/portaudio.c: implemented a PORTAUDIO_IS_SERIOUSLY_BROKEN mode (win32 asio only).

    + Gave X11 a higher priority than SDL, so that the all-in-one interface
      still works when the XVideo port is taken. If XVideo is not available,
      SDL isn't of much use though.

* src/video_output/vout_subpictures.c: proper subpicture scaling using sample aspect ratio information.

* include/vlc_es.h: added i_sar_num/den (sample aspect ratio) fields to video_format_t (will hopefully deprecate the i_aspect field one day).