The two functions featuring nNull are not particularly needed, so
I simply removed them.

Conflicts:
	modules/highgui/src/cap_msmf.hpp

Conflicts:
	modules/gpu/perf/perf_imgproc.cpp

Cast a long integer to double explicitly.

Conflicts:
	modules/python/src2/cv2.cpp

Cast some matrix sizes to type int.

Change some vector mask types to unsigned.

Conflicts:
	modules/core/src/arithm.cpp

Conflicts:
	modules/highgui/src/window_QT.cpp

A difference of two pointers was casted to unsigned which can lead to
overflow on 64-bit systems.

If used cl compiler, but generator is not Visual Studio e.g. Ninja,
enable FS option to prevent blocking PDB file in multithreaded build.

fixed mjpeg encoder so that libjpeg-based decoder does not complain on extra bytes in the end of stream