improve video image transformation to acquisition image for yuv422packed

When detector is a true video camera, in CtVideo::_InternalImageCBK::newImage() the video image is transformed in a grayscale image using lima:image2YUV() function (commmon/include/lima/VideoUtils.h). Transformation consists in just copying the Y component (luma or luminance) of the encoded video image. An other algorithm could be to transform the video image in RGB format and then sum the 3 colors in a single datum.

TO BE DISCUSSED