Add link to article for sample "Intelligent scissors"

* Add link to article

* Add autors name

* Fix whitespace

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

Update template_matching.markdown

Fixed "template image" should be "source image" in two sentences explaining template matching.

* Support Slice layer with multiple inputs

* Add test

* Supported Resize from PyTorch

* Rewrite test

* Remove Cast layer (supported in #16735)

* Support ConstantOfShape

* Fix tests

* Fix coments

* Remove useless condition

* Fixed failed tests

* Fixes issue 16777.

* core: update Concurrency getNumThreads()

Intelligent scissors

* Start

* Remove whitespace

* Re onMouse

* replased double to float

* Draw contours

* CV_FILLED -> FILLED

* Remove line 210

* Change 'about'

* Remove M_PI

* Remove warning

* CP_PI

* double to float

* CV_PI to Float

* Add struct for data

* line 172, 191 whitespace

* Change name

* Fix Warnings

* Set const

* line 180

* rewrite keys

* &img = param->img

  There's no need to use `vec_perm()` instead of `vec_splat()`,
  since instruction `vperm` is quite heavy compared to `vsplt[b,h,w]`.

* Supported Flatten for constant nodes

* Added default axis

* Refactoring

* Refactoring

* Added cast layer

* Fix comments

* Add Cast for layers

- HETERO plugin doesn't switch well between devices

- cache value, evaluate once
- better support for MINGW
- anything in 'cv' namespace
- test: dump number of active threads