Minor fix - what pip-packages are required for Python scripts

AlexeyAB

2018-05-06 c9b8bdee1886df5f83973d91c3597c28f99a9e0c

 src/voxel.c

@@ -5,6 +5,11 @@

#ifdef OPENCV
#include "opencv2/highgui/highgui_c.h"
#include "opencv2/core/version.hpp"
#ifndef CV_VERSION_EPOCH
#include "opencv2/videoio/videoio_c.h"
#endif
image get_image_from_stream(CvCapture *cap);
#endif

void extract_voxel(char *lfile, char *rfile, char *prefix)