Add support for YUV4MPEG file reading to tools files.

This CL adds support for reading .y4m files to the infra in
video_quality_analysis.cc, adding new functions 
ExtractFrameFromYuvFile() and ExtractFrameFromY4mFile(),
instad of the previous ExtractFrameFromI420(). The decision
as to which one to use is taken from the file extension,
if it is .y4m then is considered a YUV4MPEG file, otherwise
is taken as a raw .yuv file.

It also removes the pseudo duplicated function 
GetNextI420Frame(), that is used from psnr_ssim_analyzer.c,
and adds support for y4m files there.

Tested/validated via local compile-run.

YUV4MPEG is a trivial container with a file header
and a per-frame header, see [1]

[1]
http://wiki.multimedia.cx/index.php?title=YUV4MPEG2

BUG=https://code.google.com/p/chromium/issues/detail?id=343504



git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@5702 4adac7df-926f-26a2-2b94-8c16560cd09d
3 files changed