* Custom deep learning layers support

* Stack custom deep learning layers

improved performance of v_load_deinterleave(8uC3) & v_store_interleave(8uC3) intrinsics when using SSSE3 instructions.

To dump contents of the last OpenCV error

v_select 'mask' is restricted to these values only: 0 or ~0 (0xff/0xffff/etc)
mask in accuracy test is updated.

* Issue 11242 intrinsics v_extract, v_rotate improvement, branch 3.4, without C++11 (remove type restrictions for SSE2, use PALIGNR on SSSE3, compile to no-op when imm is 0 or nlanes).

* fix whitespace

* Fix #11242 (NEON intrinsics v_rotate...) branch 3.4
Separate macro expansion OPENCV_HAL_IMPL_NEON_SHIFT_OP for bitwise shifts for integers, from macro expansion OPENCV_HAL_IMPL_NEON_ROTATE for lane rotations. Bitwise shifts do not apply to floats, but lane-rotations can apply to both.

* fix whitespace

* Fix #11242 compile error (VSX intrinsics v_rotate(a)) branch 3.4 no-c++11

* Fix CV_Asserts with negation of strings

{!"string"} causes some compilers to throw a warning.

The value of the string is not that important -- it's only for printing
the assertion message.

Replace these calls with:

  CV_Error(Error::StsError, "string")

to suppress the warning.

* remove unnecessary 'break' after CV_Error()

Error messages are available via exceptions

* model is not learned when grabcut is called with GC_EVAL

* fixed test, was writing to wrong file.

* modified patch by Iwan Paolucci; added GC_EVAL_FREEZE_MODEL in addition to GC_EVAL (which semantics is retained)

  * restore resize of carotene
  * clean up the source code
  * remove unused member function (Near)
  * add strict test on the border

Reproducer:
    cmake -DCPU_BASELINE=AVX2 -DCV_DISABLE_OPTIMIZATION=ON ...

* Rewrite polar transformations

- A new wrapPolar function encapsulate both linear and semi-log remap
- Destination size is a parameter or calculated automatically to keep objects size between remapping
- linearPolar and logPolar has been deprecated

* Fix build warning and error in accuracy test

* Fix function name to warpPolar

* Explicitly specify the mapping mode, so we retain all the parameters as non-optional.

Introduces WarpPolarMode enum to specify the mapping mode in flags

* resolves performance warning on windows build

* removed duplicated logPolar and linearPolar implementations

  * use universal intrinsic instead of raw intrinsic
  * add 2 channels de-interleave on x86 platform
  * add v_int32x4 version of v_muladd
  * add accumulate version of v_dotprod based on the commit from seiko2plus on bf1852d
  * remove some verify check in performance test
  * avoid the out of boundary access and keep the performance

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

 * remove unnecessary defines from vsx_utils
 * fix v_load_expand, load lower 64bit
 * use vec_ld, vec_st with alignment load/store on all types except 64bit
 * map v_extract to v_rotate_right
 * update license header
 * enable VSX by default on clang since #11167

* Updated warpAffine test to ensure bit-exactness for CV_8U

* Updated invertAffineTransform to bit-exact evaluation

* Added custom implementation for NxN bit-exact GaussianBlur

* Reworked fixedpoint interface a bit

* Reworked horizontal line estimation for bit-exact GaussianBlur

* Reworked vertical line estimation for bit-exact GaussianBlur

* Updated range estimation for vectorized part of bit-exact GaussianBlur evaluation