* modules/packetizer/mpeg4video.c: remove the VOL from the packetized stream and put it in fmt.p_extra instead.

* modules/codec/ffmpeg/video.c: codec extra data is sometimes not available before the 1 frame is fed to the decoder.

* src/input/decoder.c: check for codec extra data changes when a packetizer is inserted before the decoder.

- automatically select SAP multicast address (closes #141)
- some clean up

   are not multithreaded.

   libmpeg2 cvs HEAD.

   a change of aspect ratio. Factorized aspect ratio code. A change of
   aspect ratio is only supported in the mosaic_bridge module, not in
   transcode.

   transcoding, transcode will take our fmt_out as a fmt_in to libmpeg2.
   libmpeg2.c will then believe that the user has requested a specific
   aspect ratio, which she hasn't. Thus in case of aspect ratio change,
   we're screwed.

   causing problem with some compiler versions.

   due to a recent change of the default value in ffmpeg which used to be
   YUV 420P). Forward i_rate in case a transcode or display operation
   takes place after switcher.

   parameter to specify the sample aspect ratio of the destination
   background. In this case, one of {width, height} can be omitted (set
   to 0) and it will be calculated based on the PAR of the source and
   the SAR of the background.

   which caused problems in case an identical PID carried the PMTs of two
   programs, one selected and the other not.

   cr_average.

(refs #87)

* Change some debugging in playlist

 I might be feeding the wrong data to the auhal core, but i'm not sure what is wrong beyond that.