* moved DIS optical flow from opencv_contrib to opencv, moved TVL1 from opencv to opencv_contrib

* fixed compile warning

* TVL1 optical flow example moved to opencv_contrib

* 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

  * remove race condition
  * upload _prevPts to OpenCL device explicitly before calling "sparse"

  - redefine 16-bit multiply operator to perform saturating multiply
    instead of non-saturating multiply
  - implement 8-bit multiply operator to perform saturating multiply
  - implement v_mul_wrap() for 8-bit, 16-bit non-saturating multiply
  - improve performance of v_mul_hi() for VSX
  - update intrin tests with new changes
  - replace unv 16-bit multiplication operator with v_mul_wrap due behavior changes

  - Several improvements depend on vpisarev review

    * initial forward declarations for universal intrinsics
    * move emulating SSE intrinsics into separate file
    * implement v_mul_expand for 8-bit
    * reimplement saturating multiply using v_mul_expand + v_pack
    * map v_expand, v_load_expand, v_load_expand_q to sse4.1
    * fix overflow avx2::v_pack(uint32)
    * implement two universal intrinsics v_expand_low and v_expand_high

* Cleanup macros and enable expansion of `__VA_ARGS__` for Visual Studio

* Macros for enum-arguments backwards compatibility

* Convert struct Param to enum struct

* Enabled ParamType.type for enum types

* Enabled `cv.read` and `cv.write` for enum types

* Rename unnamed enum to AAKAZE.DescriptorType

* Rename unnamed enum to AccessFlag

* Rename unnamed enum to AgastFeatureDetector.DetectorType

* Convert struct DrawMatchesFlags to enum struct

* Rename unnamed enum to FastFeatureDetector.DetectorType

* Rename unnamed enum to Formatter.FormatType

* Rename unnamed enum to HOGDescriptor.HistogramNormType

* Rename unnamed enum to DescriptorMatcher.MatcherType

* Rename unnamed enum to KAZE.DiffusivityType

* Rename unnamed enum to ORB.ScoreType

* Rename unnamed enum to UMatData.MemoryFlag

* Rename unnamed enum to _InputArray.KindFlag

* Rename unnamed enum to _OutputArray.DepthMask

* Convert normType enums to static const NormTypes

* Avoid conflicts with ElemType

* Rename unnamed enum to DescriptorStorageFormat

* 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

- estimateRigidTransform() is excluded from JS bindings

* video: remove duplicate RANSAC code

* remove RANSAC code video module. The module now uses RANSAC estimators from calib3d.
* deprecate estimateRigidTransform

* replace internal usage of deprecated estimateRigidTransform

* remove from wrappers
* replace usage in shape module. shape module now links to calib3d instead of video module.
* reprecate also C API version

* remove cvEstimateRigidTransform

* supress deprecated warnings in estimateRigidTransform test

* the function is now deprecated

* Pass RANSAC parameters as function input

* Clean up unnecessary code

* Keep the original function signature

* Clean up based on PR comments

Replace array with vector.

Correct naming convention for input variables.

Add checks on input variables.

* Use vector instead of array for dynamic size

* Revert change.

* Use dynamic array

* Fix wrong syntax in array allocation

* Undo change

* Fix variable name

* Use vector and not array

* fixed compile warning on Windows

Found via `codespell`

Add ocl version BackgroundSubtractorKNN (#10553)

* Add ocl version bgfg_knn

* Add ocl KNN perf test

* ocl KNN: Avoid unnecessary initializing when non-UMat parameters are used

* video: turn off OpenCL for color KNN on Intel devices

due performance degradation

* video: turn off KNN OpenCL on Apple devices with Intel iGPU

due process freeze during clBuildProgram() call

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

* fixed OpenCL functions on Mac, so that the tests pass

* fixed compile warnings; temporarily disabled OCL branch of TV L1 optical flow on mac

* fixed other few warnings on macos

If there are no OpenCL/UMat methods calls from application.

OpenCL subsystem is initialized:
- haveOpenCL() is called from application
- useOpenCL() is called from application
- access to OpenCL allocator: UMat is created (empty UMat is ignored) or UMat <-> Mat conversions are called

Don't call OpenCL functions if OPENCV_OPENCL_RUNTIME=disabled
(independent from OpenCL linkage type)

https://sourceforge.net/p/predef/wiki/OperatingSystems

Fix OpenCL's wrong output of calcOpticalFlowPyrLK function's output vector of err. Improve err's precison of the calcOpticalFlowPyrLK OpenCL function and add the relative test.

The method does cvCheckPixelBackgroundNP (which reads bgmodel)
before it is ever updated (in cvUpdatePixelBackgroundNP). This
initialization is thus needed to avoid reads of unitialized values.

Addressed comments.

1e-12 -> DBL_EPSILON