- class_info.props is a 'list'

- avoid randomized output due to unpredictable dict/set order

The character literal overload is more efficient. More info at:

http://clang.llvm.org/extra/clang-tidy/checks/performance-faster-string-find.html

original commit: 4699d2ba

Applied '@ref' linking for 3.4 Calib3D parameters and added enum cv::fisheye::CALIB_ZERO_DISPARITY == cv::CALIB_ZERO_DISPARITY == 0x400 == 1 << 10.
Fisheye test has been updated to use new enum cv::fisheye::CALIB_ZERO_DISPARITY and included CV_StaticAssert(...) to ensure cv::CALIB_ZERO_DISPARITY == cv::fisheye::CALIB_ZERO_DISPARITY.

- dst is not initialized, may include NaN values
- 0*NaN produces NaN

- configure through OPENCV_TEST_VIDEOIO_BACKEND_REQUIRE_FFMPEG environment variable

Scripts for downloading models in DNN samples

* Initial commit. Utility classes and functions for downloading files

* updated download script

* Support YAML parsing, update download script and configs

* Fix problem with archived files

* fix models.yml

* Move download utilities to more appropriate place

* Fix script description

* Update README

* update utilities for broader range of files

* fix loading with no hashsum provided

* remove unnecessary import

* fix for Python2

* Add usage examples for downloadFile function

* Add more secure cache folder selection

* Remove trailing whitespaces

* Fix indentation

* Update function interface

* Change function for temp dir, change entry name in models.yml

* Update getCacheDirectory function call

* Return python implementation for cache directory selection, use more specific env variable

* Fix whitespace

support SIMD for larger symmetric Bit-exact 16U gaussian blur

* support SIMD for bit-exact 16U symmetric gaussian blur

* use tighter SIMD registers

- detect case with infinite loop and raise NoConv exception
- handle such exception
- add support for case with missing `blobDetector` (image contains Point2f array of candidates)
- add regression test
- undone rectification for "failed" detections too
- drop redirectError() usage

Relates to OpenCV issue #18721