* Get/Set functions for BRISK parameters, issue #11527.

Allows setting threshold and octaves parameters after creating a brisk object. These parameters do not affect the initial pattern initialization and can be changed later without re-initialization.

* Fix doc parameter name.

* Brisk get/set functions tests. Check for correct value and make tests independent of default parameter values.

* Add dummy implementations for BRISK get/set functions not to break API in case someone has overloaded the Feature2d::BRISK interface. This makes BRISK different from the other detectors/descriptors on the other hand, where get/set functions are pure virtual in the interface.

- use "random" area on input image
- avoid duplicate cases

* Added performance tests for hal::norm functions

* Added sum of absolute differences intrinsic

* norm implementation updated to use wide universal intrinsics

* improve and fix v_reduce_sad on VSX

GAPI (fluid): Median blur optimization (#13329)

* GAPI (fluid): Median blur optimization: reference 3x3

* GAPI (fluid): Median blur optimization: CPU dispatcher

* GAPI (fluid): Median blur optimization: manual CV_SIMD

G-API rename GPU backend to OCL backend (#13240)

* renaming draft

* inline namespace instead non-safe define

* more back compatibility

* Updates after review from Dmitry

GAPI (fluid): Erode/Dilate optimization, part 2 (#13319)

* GAPI (fluid): Erode/Dilate optimization: hard-code 3x3 case

* GAPI (fluid): Erode/Dilate optimization: CPU dispatcher

* GAPI (fluid): Erode/Dilate optimization: speed-up 10-15x times with CV_SIMD

* GAPI (fluid): Erode/Dilate optimization: 20-30% speed-up

GAPI (fluid): Erode/Dilate optimization (#13315)

* GAPI (fluid): Erode/Dilate optimization: hard-code 3x3 case

* GAPI (fluid): Erode/Dilate optimization: CPU dispatcher

* GAPI (fluid): Erode/Dilate optimization: speed-up 10-15x times with CV_SIMD