MINOR: Printing feature stats vector error

[GeorgeTouros]

In analyze_visual.analyze_visual.py, in line 397 the shape of the feature matrix is printed instead of the shape of the feature_stats vector. Change:

print('Shape of feature stats vector including'
      ' object features (after smoothing'
      ' object confidences): {}'.format(feature_matrix.shape))

to

print('Shape of feature stats vector including'
      ' object features (after smoothing'
      ' object confidences): {}'.format(feature_stats.shape))

[pakoromilas]

@GeorgeTouros absolutely right. Thank you! It's now fixed.