avframe: add codec-independent stereoscopic metadata
h264: parse frame packing arrangement SEI messages and save relevant stereo3d information
libx264: set frame packing information when relevant information is found
mpeg12dec: parse frame packing arrangement user_data and save relevant stereo3d information
mpeg12enc: set frame packing information when relevant metadata is found
hevc: parse frame packing arrangement SEI messages and save relevant stereo3d information