Add a Y1Y2CbCr converter for 12bit sNEF files
Properly detect uncompressed RAW and RGB NEF files
Replace single D810 setup with several submodes
Set correct whitepoint on D800 uncompressed raws
Merge pull request #684 from pedrocr/add-rawspeed-crazy-nikon-subformats

Rawspeed support for the crazy Nikon subformats in the D800 and D810
Manually check for SSE3 support at startup
Merge pull request #683 from bocadillodeatun/sse3_runtime_manual_check

Manually check for SSE3 support at startup
Tiny cleanup for the last commit (a554dd67af591df020dcdb29a40c4b611b8529c8)