OpenCV: Adapt to API changes in OpenCV 4.5.2+ (#639)

* CVTracker: Handle API changes in OpenCV
The former cv::Tracker API we've been using is now cv::legacy::Tracker,
starting in OpenCV 4.5.1.

* CVTracker: Move some includes, add std:: prefixes

* Move ClipProcessingJobs into openshot NS

* OpenCV 4.5.1 message and auto-disabling

* Add fstream includes, explicit std:: namespace
Work around a MacOS bug where bare fstream resolves to the wrong class.

Co-authored-by: Brenno <brenno.caldato@gmail.com>
Co-authored-by: Brenno A. C. Caldato <BrennoCaldato@users.noreply.github.com>

src/CVObjectDetection.cpp

@@ -28,6 +28,10 @@
  * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <fstream>
+#include <iomanip>
+#include <iostream>
+
 #include "CVObjectDetection.h"
 #include <google/protobuf/util/time_util.h>