API. ByteCount positions are not supported anymore.

* modules/access_output/udp.c: if a packet is bigger than the mtu size, we emit a warning and try to split it.

* modules/mux/mpeg/ps.c: make sure the data blocks containing the pack and system headers are timestamped correctly. Added an --sout-ps-dts-delay option.

* src/playlist/item.c: fixed recent playlist item initialization bug which was screwing up things like doing random autodeletions, etc...

  fen: any suggestions for the other Control() stuff?

   - searching is a mess
   - autodetect not yet activated, force by opening the idx as subfile

* src/video_output/vout_subpictures.c: modify the scaling factor based on the original video size info.

    + Fixed previously broken DVD support.
    + Removed currently broken Speex support.
  * debian/control:
    + Build-depend on libdvdnav.

  TODO: create the index
        position control

* modules/video_filter/time.c: stick to our config options naming convention + fixed a couple of mem-leaks.

   + major cleanup and bug fixing.
   + added support for spawning and controlling several media instances.