* fix Scharr nomination

Parallelize pyrDown & calcSharrDeriv

* ::pyrDown has been parallelized

* CalcSharrDeriv parallelized

* Fixed whitespace

* Set granularity based on amount of threads enabled

* Granularity changed to cv::getNumThreads, now each thread should receive 1/n sized stripes

* imgproc: move PyrDownInvoker<CastOp>::operator() implementation

* imgproc(pyramid): remove syloopboundary()

* video: SharrDerivInvoker replace 'Mat*' => 'Mat&' fields

* Convert lkpyramid from SSE SIMD to HAL - 90% faster on Power (VSX).

* Replace stores with reduce_sum.  Rework to handle endianess correctly.

* Fix compiler warnings by casting values explicitly to shorts

* Switch to CV_SIMD128 compiler definition.  Unroll loop to 8 elements since we've already loaded the data.

- use compile-time checks instead (`#if CV_SIMD128`)
- runtime checks are useless

  * 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

* 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`

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)

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.

OpenVX optical flow PyrLK wrappers added (#7774)

* wrappers for vx_pyramid added

* initial version of Optical Flow PyrLK wrappers added

* array downloading code simplified

* disabled due to bad accuracy; fixed bugs, e.g. vendor-specific ones

* rewritten for new macro use

Operations inside for loops are unnecessary. They are repeated anyway just below for loops

IPP can be switched on and off on runtime;

Optional implementation collector was added (switched off by default in CMake). Gathers data of implementation used in functions and report this info through performance TS;

TS modifications for implementations control;

1. someMatrix.data -> someMatrix.prt()
2. someMatrix.data + someMatrix.step * lineIndex -> someMatrix.ptr( lineIndex )
3. (SomeType*) someMatrix.data -> someMatrix.ptr<SomeType>()
4. someMatrix.data -> !someMatrix.empty() ( or !someMatrix.data -> someMatrix.empty() ) in logical expressions