OpenCV 3.4.0-rc

fixes CUDA build

Move SimulatedAnnealingSolver::Impl in cpp file

* kmeans: number of channels in _centers fixed

* fixedType() is checked now

Fix file names

* update createsamples

adds command-line option -rngseed
replaces rand() -> theRNG()

* Update utility.cpp

* apps(createsamples): fix warpPerspective pixels access bug

dnn: more debug information

- fix conversion intrinsics compatibility with xlc
- implement odd-elements 2 to 4 conversion intrinsics
- improve implementation of universal intrinsic v_popcount
- rename FORCE_INLINE to VSX_FINLINE in vsx_utils.hpp

* Simulated Annealing for ANN_MLP training method

* EXPECT_LT

* just to test new data

* manage RNG

* Try again

* Just run buildbot with new data

* try to understand

* Test layer

* New data- new test

* Force RNG in backprop

* Use Impl to avoid virtual method

* reset all weights

* try to solve ABI

* retry

* ABI solved?

* till problem with dynamic_cast

* Something is wrong

* Solved?

* disable backprop test

* remove ANN_MLP_ANNEALImpl

* Disable weight in varmap

* Add example for SimulatedAnnealing

* Fix issue #10114
Convert table change
From:
CV_8U -> HALF
CV_8S -> HALF
CV_16U -> UINT
CV_16S -> UINT
CV_32S -> UINT
CV_32F -> FLOAT
To:
CV_8U -> HALF
CV_8S -> HALF
CV_16U -> UINT
CV_16S -> FLOAT
CV_32S -> FLOAT loss precision
CV_32F -> FLOAT
Signed integer can't be presented well with UINT. Even adjust bias, CV16S and CV32S will be confused when load from exr file.
Also fix CV_8S negative value incorrect bug

* EXR import and export
imread() from EXR returns CV_32F only
imwrite() accepts CV_32 cv::Mat only and stores FLOAT images by default. Add imwrite() flag to store in HALF format.

* fix compiling error

* clean up

* fix EXR import issues

* remove raw SSE2/NEON implementation from convert.cpp
  * remove raw implementation from Cvt_SIMD
  * remove raw implementation from cvtScale_SIMD
  * remove raw implementation from cvtScaleAbs_SIMD
  * remove duplicated implementation cvt_<float, short>
  * remove duplicated implementation cvtScale_<short, short, float>
  * add "from double" version of Cvt_SIMD
  * modify the condition of test ConvertScaleAbs

* Update convert.cpp

fixed crash in cvtScaleAbs(8s=>8u)

* fixed compile error on Win32

* fixed several test failures because of accuracy loss in cvtScale(int=>int)

* fixed NEON implementation of v_cvt_f64(int=>double) intrinsic

* another attempt to fix test failures

* keep trying to fix the test failures and just introduced compile warnings

* fixed one remaining test (subtractScalar)