The `CV_RGB` macro is now in `imgproc.hpp`.
Fixes:
../subprojects/gst-plugins-bad/ext/opencv/gsthanddetect.cpp:497:40: error: ‘CV_RGB’ was not declared in this scope
cvCircle (img, center, radius, CV_RGB (0, 0, 200), 1, 8, 0);
^~~~~~
Update pyramidsegment to inherit from GstOpencvVideoFilter instead of from
GstElement. This means less code and more uniformity with other OpenCV
elements.
The opencv element includes were full of duplicates and uneeded headers.
For example a few elements that stopped using gstcvopencvutils still
included that header file.
