Add a new type u24.
Fix someting wrong.
More work in sceJpegDecodeMJpegYCbCr.
Implemented sceJpegMJpegCsc.
Rename u24 to u24_be.
Rename __JpegDecodeMJpegYCbCr to __JpegConvertRGBToYCbCr.
Merge pull request #4035 from shenweip/patch-12

Implemented sceJpegDecodeMJpegYCbCr and sceJpegMJpegCsc.