- initialize arithmetic dispatcher
  - add new universal intrinsic v_absdiffs
  - add new universal intrinsic v_pack_b
  - add accumulate version of universal intrinsic v_round
  - fix sse/avx2:uint8 multiplication overflow
  - reimplement arithmetic, logic and comparison operations into wide universal intrinsics
    with full support for all types
  - reimplement IPP arithmetic, logic and comparison operations in a sperate file arithm_ipp.hpp
  - avoid scalar multiplication if scaling factor eq 1 and use integer multiplication
  - move C arithmetic operations to precomp.hpp and delete [arithm_simd|arithm_core].hpp
  - add compatibility with new opencv4 divide policy

- always pass DEPTH_dst value to core/arithm kernel

* 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

* simplify condition

* dims must > 0 or latter sz[dims-1] will underflow

Commits:
- 09837928
- 10fb88d0

Excluded changes with std::atomic (C++98 requirement)

* fix some static analyzer warnings

* fix some static analyzer warnings

* fix race condition of workthread control

fixes handling of empty matrices in some functions (#11634)

* a part of PR #11416 by Yuki Takehara

* moved the empty mat check in Mat::copyTo()

* fixed some test failures

  * remove raw NEON/SSE2 implementation as much as possible
  * replace them to universal intrinsic in InRange/Compare/AddWeighted

- don't use undefined flag=0. It should be CONSTANT instead.
- don't allow 'UMat* m=NULL' argument (except LOCAL/CONSTANT flags).
  This case is not handled well to provide NULL __global pointers.
  It is better to use '-D' macro defines instead (at least for performance)

(2.4) Backports from master branch (#7854)

- added HAL documentation support
- added documentation to HAL replacement interface
- updated several HAL functions in imgproc module

- added new functions from core module: split, merge, add, sub, mul, div, ...
- added function replacement mechanism
- added example of HAL replacement library

fixed http://code.opencv.org/issues/3935
possibly fixed http://code.opencv.org/issues/3594