Fix doxygen comment in BFMatcher

numpy 1.13.0+

- '-fvisibility' flag was updated
- PVAPI library detection was changed

Fixing explicitly call download method for cuda::GpuMat object

[GSOC] Enable OCL for AKAZE (#9330)

* revert e0489cb4 - reenable OCL for AKAZE

* deal with conversion internally in AKAZE

* pass InputArray directly to AKAZE to allow distiguishing input Mat/UMat. deal with conversion there
* ensure that keypoints orientations are always computed. prevents misuse of internal AKAZE class.

* covert internal AKAZE functions to use InputArray/OutputArray

* make internal functions private in AKAZE

* split OCL and CPU paths in AKAZE

* create 2 separate pyramids, 1 for OCL and 1 for CPU
* template functions that use temporaries to always store them as correct type (UMat/Mat)

* remove variable used only in OCL path

causes unused variable warning

* update AKAZE documentation

* run ocl version only when ocl is enabled

* add tests for OCL path in AKAZE

* relax condition for keypoints angle

Version: gcc (GCC) 7.1.1 20170622 (Red Hat 7.1.1-3)
Flags: -fsanitize=address,undefined

SoftFloat: added sin, cos and docs (#9329)

* softfloat: comparison operators made inline, min() max() eps() isSubnormal() added

* softfloat: get/set sign/exp

* softfloat: get/set frac

* softfloat: tests rewritten with new tools

* softfloat: added pi(), sin(), cos()

* softfloat: more comments

* softfloat: updated sincos arg reduction

* softfloat: initial tests for sincos added

* softfloat: test works, code cleanup is pending

* softfloat: sincos argreduce rewritten

* softfloat: sincos refactored and simplified

* softfloat sincos: epsilons calibrated

* softfloat: junk code removed from tests

* softfloat: docs added

* inline comparisons undone; warning fixed

- eliminate legacy C code, used fields
- fix mutex synchronization issues
- set trackbar min/max without unnecessary truncation; allow negative values