Merge remote-tracking branch 'qatar/master'

Merge remote-tracking branch 'qatar/master'

* qatar/master:
  AVOptions: fix av_set_string3() doxy to match reality.
  cmdutils: get rid of dummy contexts for examining AVOptions.
  lavf,lavc,sws: add {avcodec,avformat,sws}_get_class() functions.
  AVOptions: add AV_OPT_SEARCH_FAKE_OBJ flag for av_opt_find().
  cpu detection: avoid a signed overflow

Conflicts:
	avconv.c
	cmdutils.c
	doc/APIchanges
	ffmpeg.c
	libavcodec/options.c
	libavcodec/version.h
	libavformat/version.h
	libavutil/avutil.h

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