riff: add SMV2 FourCC for H264

Sample-Id: smv2.avi
riff: add H264 from QNAP Systems
riff: Add V264 for H264 in CCTV recordings
riff: add FourCC for GeoVision cameras
riff: Support H.264 fourcc UMSV
riff: add "lsvm" FourCC for H263.
riff: add G264 to mpeg4, only decodes keyframes
riff: add DM4V FourCC
riff: add DYM4 mpeg4 fourcc
riff: add "SM4V" FourCC
riff: Support decoding ASP variant from QNAP Systems
riff: add PLV1 fourcc to mpeg4

Sample-Id: york-water-meteor.avi
riff: add "GXVE" FourCC for WMV2

Sample-Id: vivd.avi
riff: add dvis/pdvc FourCCs
riff: Support NTSC forward dvcpro videos

PAL looks incorrect.
riff: Add SLDV FourCC for dvvideo
riff: support BW10 as mpeg1
riff: Support XMPG as mpeg1
riff: Add "S263" FourCC
riff: add "YUV8" FourCC

Sample-Id: MAILTEST.AVI