Fix headers for opencv2 and later

opencv/cv.h is removed on opencv4

Signed-off-by: Nicolas Chauvet <[email protected]>

Author: kwizart

wrappers/opencv/cvdemo.cpp

@@ -1,5 +1,4 @@
-#include <opencv/cv.h>
-#include <opencv/highgui.h>
+#include <opencv2/highgui/highgui_c.h>
 #include <stdio.h>
 #include "libfreenect_cv.h"
 

wrappers/opencv/libfreenect_cv.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <opencv/cv.h>
+#include <opencv2/core/core_c.h>
 
 #ifdef __cplusplus
 extern "C" {