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>

tests/Point.cpp

@@ -29,13 +29,14 @@
  */
 
 #include <catch2/catch.hpp>
-
+#include <sstream>
 #include "Point.h"
 #include "Enums.h"
 #include "Exceptions.h"
 #include "Coordinate.h"
 #include "Json.h"
 
+
 TEST_CASE( "default constructor", "[libopenshot][point]" )
 {
 	openshot::Point p;