pull 'hog diff' into its own function
perfect match for voc5 and streamHog in computeCells. (only difference is the LUT)
looks like autovectorizer is happy with hogCell_gradientEnergy. gonna leave it alone.
setting up voc5 cells-> blocks normalization
with omp, normalizeCells is <1ms for 1 scale. (havent checked correctness)
texture features