GAPI (fluid): RGB to Lab optimization (#13206)

* GAPI (fluid): BGR2LUV, RGB2Lab: performance test

* GAPI (fluid): BGR2LUV, RGB2Lab: using cv::hal::cvtBGRtoLab

* GAPI (fluid): BGR2LUV, RGB2Lab: hide reference code with #ifdef

GAPI (fluid): RGB to YUV optimization (#13174)

* GAPI (fluid): RGB to YUV: activate performance tests

* GAPI (fluid): speedup 4-8x RGB-to-YUV, 2.5x YUV to RGB with int16 arithmetic

* GAPI (fluid): RGB <--> YUV: fixed compiler warning

* GAPI (fluid): RGB <--> YUV: additional speedup 2-3x times (10-15x over original) via manual CV_SIMD

* GAPI (fluid): RGB <--> YUV: dynamic CV_SIMD dispatching

OpenCV 4.0.0

OpenCV 4.0.0 for Intel(R) OpenVINO(TM) toolkit

OpenCV 3.4.4

OpenCV 3.4.4

* samples: rename starter_imagelist.cpp

* samples: rename intelperc_capture.cpp => videocapture_intelperc.cpp

* samples: rename openni_capture.cpp => videocapture_openni.cpp

* samples: rename image_sequence.cpp => videocapture_image_sequence.cpp

* samples: rename gstreamer_pipeline.cpp => videocapture_gstreamer_pipeline.cpp

* samples: rename autofocus.cpp => videocapture_gphoto2_autofocus.cpp

* samples: rename live_detect_qrcode.cpp => qrcode.cpp

G-API: Doxygen class reference

* G-API Doxygen documentation: covered cv::GComputation

* G-API Doxygen documentation: added sections on compile arguments

* G-API Doxygen documentation: restructuring & more text

* Added new sections (organized API reference into it);
* Documented GCompiled, compile args, backends, etc.

* G-API Doxygen documentation: documented GKernelPackage and added group for meta

* Add support for ConvTranspose when parsing ONNX.

* Add support for ConvTranspose when parsing ONNX.

* Add test for Deconvolution

broken in 11eafca3

  - update parameter in carotene

Configures and loads OpenCV bindings extension including 3rdparty dependencies

Based on running Python specify:
- configure PYTHON_PATH (via "sys.path")
- configure LD_LIBRARY_PATH / PATH