Uses mkstmp() with directory being the same as the test data
directory to create temporary output file. For Windows
GetTempFileNameA() function is used.

Change-Id: Ie4681b2b4f44f8c22d3b3faf134c44087b484f94

The y4m extension used is the same as the one used in ffmpeg/x264.
The patch is adapted from the highbitdepth branch.

Also adds unit tests for y4m header parsing and md5 check
of the raw frame data, as well as y4m writing.

[build fix for Mac/VS by not using tuples with strings]

Change-Id: I40897ee37d289e4b6cea6fedc67047d692b8cb46

Reverting "Adds support for reading and writing 10/12-bit y4m" for now because of Mac Build Failure.

This reverts commit 82dc1332

Change-Id: I824bf42bf47c7df6985c79e451d6af913030d374

The y4m extension used is the same as the one used in ffmpeg/x264.
The patch is adapted from the highbitdepth branch.

Also adds unit tests for y4m header parsing and md5 check
of the raw frame data, as well as y4m writing.

Change-Id: Ie2794daf6dbafd2f128464f9b9da520fc54c0dd6

Fix of https://code.google.com/p/webm/issues/detail?id=698 issue.

Change-Id: I7a92d91481dbbae28d8953f146e9faafdcd7a310

Change-Id: I03f614872167841515a74740d654c008b60104a4