* remove NVidia and Nvidia
  * replace Cuda with CUDA
  * keep the letters for API

Found via `codespell`

* add HAL for SobelFilter
* add HAL for pyrDown
* add HAL for Scharr

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)

- Optimizations set change. Now IPP integrations will provide code for SSE42, AVX2 and AVX512 (SKX) CPUs only. For HW below SSE42 IPP code is disabled.
- Performance regressions fixes for IPP code paths;
- cv::boxFilter integration improvement;
- cv::filter2D integration improvement;

* OpenVX HAL updated to use generic OpenVX wrappers

* vxErr class from OpenVX HAL replaced with ivx::WrapperError

* reduced usage of vxImage class from OpenVX HAL replaced with ivx::Image

* vxImage class rewritten as ivx::Image subclass that calls swapHandle prior release

* Fix OpenVX HAL build

* Fix for review comments

This ocl kernel is 46%~171% faster than current laplacian 3x3
ocl kernel in the perf test, with image format "CV_8UC1".
Signed-off-by: Li Peng <peng.li@intel.com>

It improves 108%~230% performance in the perf test
with image format "CV_8UC1" and kernel size 3.
Signed-off-by: Li Peng <peng.li@intel.com>

OPENCV_IPP env var now allows to select IPP architecture level for IPP9+;
IPP initialization logic was unified across modules;

HAVE_IPP_ICV_ONLY will be undefined if OpenCV was linked against ICV packet from IPP9 or greater. ICV9+ packets will be aligned with IPP in OpenCV APIs
This will ease code management between IPP and ICV

IPP_VERSION_MAJOR * 100 + IPP_VERSION_MINOR*10 + IPP_VERSION_UPDATE
to manage changes between updates more easily.

IPP_DISABLE_BLOCK was added to ease tracking of disabled IPP functions;

Minor changes to IPP implementations;

Removed IPP port for tiny arithm.cpp functions

Additional warnings fix on various platforms.

Build without OPENCL and GCC warnings fixed

Fixed warnings, trailing spaces and removed unused secure_cpy.

IPP code refactored.

IPP code path  implemented as separate static functions to simplify future work with IPP code and make it more readable.

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;