* Kinect2 support added to OpenNI2 backend

* more fixes for OpenNI2 backend

* whitespace fixed

* libfreenect2 support added

* const cast added

* mutable removed

OPENCV_OCL4DNN_FORCE_AUTO_TUNING should ignore existed configuration from:
- builtin predefined configurations (for Intel OpenCL iGPUs)
- external configuration (via OPENCV_OCL4DNN_CONFIG_PATH)

Prefer external configuration over builtin.

`dest(roi_d)` operation contains similar check inside.

Use Win32 TRUE/FALSE in SetUINT32() calls for bool parameters

Corrected formula for weighted within-class variance

to control DNN_BACKEND_DEFAULT enumeration value behavior

`camid` value is always -1 after close().

* setTo_#10507

* setTo_Nan_10507

* setTo: update check / test for NaNs

Add Java and Python code for the following imgproc tutorials: Finding contours in your image, Convex Hull, Creating Bounding boxes and circles for contours, Creating Bounding rotated boxes and ellipses for contours, Image Moments, Point Polygon Test.