Merge remote-tracking branch 'qatar/master'

* qatar/master:
  libmp3lame: add missing layout terminator
  avconv: multithreaded demuxing.
  Bump lavu minor and add an APIChanges entry for audioconvert functions.
  audioconvert: add a function for extracting the channel with the given index
  audioconvert: add a function for getting the name of a single channel.
  audioconvert: add a function for getting channel's index in layout
  audioconvert: use av_popcount64 in av_get_channel_layout_nb_channels
  vf_libopencv: add missing headers.
  iac: add missing dependency

Conflicts:
	configure
	doc/APIchanges
	ffmpeg.c
	libavcodec/libmp3lame.c
	libavutil/avutil.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>