* Implement NV12toGray

* Snapshot

* Implement NV12toGray as compound kernel

* Update gapi_imgproc_tests_inl.hpp

* Remove YUV2Gray from public API

Usage:
- cmake -DOPENCV_INSTALL_APPS_LIST=opencv_version ...

* Add android support for tengine

* modify tengine download use commit id

* Del some invalid log in Tengine

* Test. default enable tengine

* ndk version judegment

* Close test . set Tengine default OFF

* Logic problem

* test .Android NDK judgement .

* Cmake error modify.

* cmake: cleanup tengine scripts

* cmake: use tengine target name

* cmake: disable testing of BUILD_ANDROID_PROJECTS=OFF

* Close test .

Add link to article for sample "Intelligent scissors"

* Add link to article

* Add autors name

* Fix whitespace

G-API: Implement WarpAffine

* Add WarpAffine

* Ban BORDER_TRANSPARENT

* Fix doc

the float variant was always shadowed by the int version as
Rect2d is implicitly convertible to Rect.
This swaps things which is fine, as the vector of boxes was always
copied and the computation was done in double.

- python-3.x => python-3
- config-3.x.py => config-3.py

Added DaSiamRPN tracker

* added DaSiamRPN tracker

* whitespace trouble handled

* Fixes for PR

* Fixes for PR

* Fixes for PR

* added new line in the end of the file and x_crop fix

* removed cxy_wh_2_rect function

* removed loop from sofrmax function

* more  detailed discription about absolute paths to onnx models

* removed nested while loop, initialization moved from main tracking loop

* added assert message for small init bb

* initial bounding box on videostream

* selection of initial bounding box improved

* created tracker class, fixed initializing bounding box

* fix round of value

* names fix

* private methods renamed

* names fixed, case for video WIP

* fix case with video

* removed hardcoded size of window

* whitespace fix

* links to models fixed

* bounding box drawing fix

* changes does not required

* code style fixes

* fixes

* frame checker added in tracking loop

* fixed import sys

Some debian package manager tweaks