* Improve documentation.

* Update imgproc.hpp

Implement cv::cuda::calcHist with mask support (#8367)

* Implement cuda::calcHist with mask

* Fix documentation build warning

* Have their own step sizes for src and mask. Fix review comment.

3.2 version doesn't support 4 channel color image
detections, unlike 3.1. Now, we don't call
CV_Error() if 4 channel image is given.

resolve #8326

`template<typename _Tp> inline const _Tp* Mat_<_Tp>::operator [](int y) const` does not support 3d matrix since it checks rows.

This operator[] shall check size.p[0] instead.

Make it more clear for the type of input argument.

Synchronizing against non-final fields is advised against.

* Use the YV12 format in the Android emulator to avoid image issues

* Removed trailing spaces

* Added exception in else case

* Removed tab

create a dummy gzFile type

the "std::basic_ios::operator bool" differs between C++98 and C++11. The
"double not" syntax is portable and covers both cases with equivalent
meaning

force other RNG seed

std::rand() has no thread-safe guarantee.

Fix issue #8280: "fastmath.h related compile errors with Embarcadero C++ Builder 10.1"

Finished with several samples support, need regression testing

Gave a more relevant name to function (getVotes)

Finished implicit implementation

Removed printf, finished regresion testing

Fixed conversion warning

Finished test for Rtrees

Fixed documentation

Initialized variable

Added doxygen documentation

Added parameter name

medianBlur called with "empty" source and ksize >= 7 crashes application with accessviolation. With this extra assert this is avoided and the application may normally catch the thrown exception.