- check boundary strictly
 - initialize the variable before using it

Warping a matrix with more than 4 channels using BORDER_CONSTANT and
INTER_NEAREST, INTER_CUBIC or INTER_LANCZOS4 interpolation led to
undefined behaviour. This commit changes the behavior of these methods
to be similar to that of INTER_LINEAR. Changed the scope of some of the
variables to more local. Modified some tests to be able to detect the
error described.

#resolves: 7881

remove printf statement and associated variables from invMapPointSpherical() in undistort.cpp

medianBlur called with "empty" source and ksize >= 7 crashes application with accessviolation. With this extra assert this is avoided and the application may normally catch the thrown exception.

 - brush up the implementation

 - add more channels/depth performance test for blend

- don't use undefined flag=0. It should be CONSTANT instead.
- don't allow 'UMat* m=NULL' argument (except LOCAL/CONSTANT flags).
  This case is not handled well to provide NULL __global pointers.
  It is better to use '-D' macro defines instead (at least for performance)

 - let it possible to reach Bayer2BGRA conversion

 - make sure SSE version will be still available for backward compatibility

Add check for all zero moments. If one of the shapes is empty, the match would return zero distance between the shapes even when the other one had content. It now returns DBL_MAX if no moments had value.

* OpenVX HAL updated to use generic OpenVX wrappers

* vxErr class from OpenVX HAL replaced with ivx::WrapperError

* reduced usage of vxImage class from OpenVX HAL replaced with ivx::Image

* vxImage class rewritten as ivx::Image subclass that calls swapHandle prior release

* Fix OpenVX HAL build

* Fix for review comments

OpenVX pyrDown wrappers (#7793)

* wrappers for vx_pyramid added

* initial version of pyrDown() wrapper added

* disabled for Khronos

* rewritten for new macro use; border mode added to node