* commit 'c4bfa098':
  Add a WebP decoder

Conflicts:
	Changelog
	doc/general.texi
	libavcodec/Makefile
	libavcodec/avcodec.h
	libavcodec/version.h
	libavformat/img2.c

The previously existing webp decoder is disabled as the new
one supports lossless mode and alpha while the previous does not.
Merged-by: Michael Niedermayer <michaelni@gmx.at>