Implement GArik's comments

Remove unnecessary c_str()

Fix brace position

Supported ONNX Squeeze, ReduceL2 and Eltwise::DIV

* Support eltwise div

* Fix test

* OpenCL support added

* refactoring

* fix code style

* Only squeeze with axes supported

Fix an error during Windows installation caused by trying to create the already existing Build directory. Also excluding intermediate steps for Install directory creation.

* Grammar fixes for python core operations docs

* fixed whitespace error

* reverted changes

Signed-off-by: SSE4 <tomskside@gmail.com>

It's not an error if some OpenCL platform has no devices. This makes
OpenCL device detection work correctly in the following scenario:

$ OPENCV_OPENCL_DEVICE=:GPU: ./opencv_test_dnn

OpenCV version: 4.1.2-dev
OpenCV VCS version: 4.1.2-80-g467748ee98-dirty
Build type: Debug
Compiler: /usr/bin/g++  (ver 7.4.0)
Parallel framework: pthreads
CPU features: SSE SSE2 SSE3 *SSE4.1 *SSE4.2 *FP16 *AVX *AVX2 *AVX512-SKX?
Intel(R) IPP version: ippIP AVX2 (l9) 2019.0.0 Gold (-) Jul 24 2018
OpenCL Platforms:
    AMD Accelerated Parallel Processing
    Portable Computing Language
        CPU: pthread-AMD Ryzen 7 2700X Eight-Core Processor (OpenCL 1.2 pocl HSTR: pthread-x86_64-pc-linux-gnu-znver1)
    NVIDIA CUDA
        dGPU: GeForce GTX 1080 (OpenCL 1.2 CUDA)
Current OpenCL device:
    Type = dGPU
    Name = GeForce GTX 1080
    Version = OpenCL 1.2 CUDA
    Driver version = 430.26

* Convert moments in tile algorithms to HAL (1.3x faster for VSX).

* Adding NEON code back in for non 64-bit platforms.

* Remove floats from post processing.

- added removal of temporary file

* Reduce code nesting
* Drop redundant .c_str() calls

Correct stereoRectify documentation

Fix wrong definition of viz::Color::navy()

Clarify stereoRectify() doc

The function stereoRectify() takes as input a coordinate transform between two cameras. It is ambiguous how it goes. I clarified that it goes from the second camera to the first.

* Use FlsAlloc/FlsFree/FlsGetValue/FlsSetValue instead of TlsAlloc/TlsFree/TlsGetValue/TlsSetValue to implment TLS value cleanup when thread has been terminated on Windows Vista and above

* Fix 32-bit build

* Fixed calling convention of cleanup callback

* WINAPI changed to NTAPI

* Use proper guard macro

* Vectorize flipHoriz and flipVert functions.

* Change v_load_mirror_1 to use vec_revb for VSX

* Only use vec_revb in ISA3.0

* Removing vec_revb code since some of the older compilers don't fully support it.

* Use new v_reverse intrinsic and cleanup code.

* Ensure there are no alignment issues with copies

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

* Changes disparity image to float representation
Signed-off-by: Connor James Smith <cjs.connor.smith@gmail.com>

* samples: update disparity multiplier handling in stereo_match.cpp

* Doc bugfix

The documentation page StereoBinaryBM and StereoBinarySGBM says that it returns a disparity that is scaled multiplied by 16. This scaling must be undone before calling reprojectImageTo3D, otherwise the results are wrong. The function reprojectImageTo3D() could do this scaling internally, maybe, but at least the documentation must explain that this has to be done.

* calib3d: update reprojectImageTo3D documentation

* calib3d: add StereoBM/StereoSGBM into notes list