apng_parser.c 

based on png_parser.c . chunks parsed based on fcTL and IHDR.
Update apng_parser.c
Update apng_parser.c

fcTL detected and next put to before chunk-length bytes
Update avcodec.h

added codec id for apng
Update allcodecs.c

registered parser and decodec for APNG
Create apngdec.c
Merge remote-tracking branch 'upstream/master'

addE
Merge branch 'master' of https://github.com/26mansi/FFmpeg