* a part of https://github.com/opencv/opencv/pull/11364 by Tetragramm. Rewritten and extended findNonZero & PSNR to support more types, not just 8u.

* fixed compile & doxygen warnings

* fixed small bug in findNonZero test

* Include ELA example

* Include ELA example

* Include ELA example

* Include ELA example

* Include ELA example

* Include ELA example

* Include ELA example

* Include ELA example

* Include ELA example

* Include ELA example

* Include ELA example

* did some code cleanup

* fixed compile error

* optimize ocl kernel enqueue in fc layer
Signed-off-by: Li Peng <peng.li@intel.com>

* use CV_LOG_INFO in convolution auto tuning
Signed-off-by: Li Peng <peng.li@intel.com>

* update convolution IDLF kernel

extend parameter tuning range, also cleanup
ocl kernel implementation
Signed-off-by: Li Peng <peng.li@intel.com>

* update in-memory convolution cache config

fp16 and fp32 cache config are stored separately
Signed-off-by: Li Peng <peng.li@intel.com>

* apps: add Win32 friendly opencv_version app

Improve experience of launching app from explorer:
- application just flash (open/close) the console window
Suggested Win32 application flavor additionally shows MessageBox
and waits for User interaction.

* cmake: added unified application creation function

* 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