Several fixes for OpenVX wrappers (#7782)
* Several fixes added to ivx.hpp:
* `#include <VX/vxu.h>`
* `vx_keypoint_t` support added
* type check fixed
* fixed Node::create() for >6 args in c++98
* fixed Array::copyFrom() if array is empty
* type check changed; Array::addItem methods changed
OpenVX C++ wrappers docs (#7681)
* adding wrapper headers to the project to see them in IDE project explorer
* readme
* doxygen: toplevel brief-s
* more doxygen
* more doxygen
C++ wrappers over OpenVX 1.x API (#7550)
* initial commit
* fixing missing swap(refcount) bug
* removing dead code
* fixinf identation
* splitting c++98 and external refcount definitions
* fixing formatToMatType
* using vector instead of initializer_list for consistency with c++98 API
* IVX_HIDE_INFO_WARNINGS
* just in case a compiler doesn't do this
* removing copy functionality from ImagePatch, Image can be used for that
* stricter type checks