* removed C API in the following modules: photo, video, imgcodecs, videoio

* trying to fix various compile errors and warnings on Windows and Linux

* continue to fix compile errors and warnings

* continue to fix compile errors, warnings, as well as the test failures

* trying to resolve compile warnings on Android

* Update cap_dc1394_v2.cpp

fix warning from the new GCC

* may be an typo fix

* remove identical branch,may be paste error

* add parentheses around macro parameter

* simplify if condition

* check malloc fail

* change the condition of branch removed by commit 3041502861318c85d901e8c08226ff67898c77ed

	* Keep image aspect ratio in resize called in grad_system and
weak_order
	* Bug correction in loop inside Decolor::gradvector

`dest(roi_d)` operation contains similar check inside.

- leads to errors due 'const' modifier of getMat() method
- may be non-optimal with non-CPU data storage

This avoids MSVC 19.14.26428.1 to call vectorized __vdecl_cosf4() function with less precision.

Refactor decolor (#11035)

* decolor: modernize deprecated headers (math.h -> cmath)

* refactor contrast_preserve.cpp

* refactor contrast_preserve.hpp (add static/const)

* refactor contrast_preserve.hpp (join assignment and declaration)

* refactor contrast_preserve.hpp (format)

* refactor test_decolor.cpp (indent)

* refactor contrast_preserve.hpp (const)

* contrast_preserve.hpp : optimize by minMaxLoc

* fix trailing-whitespace

* fix warning C4267 on VC++ x64
(conversion from 'size_t' to 'int', possible loss of data)

* use cvRound instead of round_num

* decrease indentation of test_decolor.cpp

* remove pow() to optimize

* remove redundant Mat initialization

* optimized cv::decolor by removing vector.push_back

* restored CV_INSTRUMENT_REGION() and original indent

* fix build warnings in contrast_preserve.hpp

* undo refactoring contrast_preserve.cpp/hpp

* clean npr functions of useless initializations (speed-up)

* photo: remove unnecessary code

Implementation of bit-exact resize. Internal calls to linear resize updated to use bit-exact version. (#9468)

fixed unnecessary reconstruction in seamlessclone by using only the
required rectangular area in input images

Remove unnecessary Non-ASCII characters from source code (#9075)

* Remove unnecessary Non-ASCII characters from source code

Remove unnecessary Non-ASCII characters and replace them with ASCII
characters

* Remove dashes in the @param statement

Remove dashes and place single space in the @param statement to keep
coding style

* misc: more fixes for non-ASCII symbols

* misc: fix non-ASCII symbol in CMake file

There is no cast to wide integer type:
    std::numeric_limits<ST>::max() * std::numeric_limits<ST>::max()