fixed many bugs related to Mat::getUMat(), asynchronous kernel execution etc. Also, played a bit with ocl::cvtColor vs cv::cvtColor performance

removed refcount field from Mat; that helped to find and eliminate some memory leaks. perf tests should probably pass now

hopefully, fixed compile errors on Win & Linux; fixed getMatVector() so core & imgproc tests now pass; fixed doc builder errors

* switch to InputArray/OutputArray
* add Stream support

* Drop some low level API
* Remove outdated overloads
* Utilize Input/OutputArray

e.g. <opencv2/core/core.hpp> become <opencv2/core.hpp>

Also renamed <opencv2/core/opengl_interop.hpp> to <opencv2/core/opengl.hpp>

Fixed issues: #2737 #2848

rewritten several functions from calib3d: findhomography, findfundamentalmat, findessentialmat, estimateaffine3d, computecorrespondepilines, convert points{to/from}homogeneous to C++.

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

* removed OpenGLFuncTab, now extensions are loaded internally
* added support of GlBuffer and GlTexture2D to InputArray/OutputArray
* added ELEMENT_ARRAY_BUFFER and PIXEL_PACK_BUFFER targets
* added copyFrom/copyTo method for GlBuffer and GlTexture2D
* removed GlFont
* removed pointCloudShow
* removed OpenGLCleanCallback
* added Access parameter to GlBuffer::mapHost
* added autoRelease parameter to all create methods