Fixes #7603, which was caused by OCVViewPort::icvmouseProcessing
not being declared as virtual, and hence was not overriden by
DefaultViewPort::icvmouseProcessing (which does the inverse
coordinate mapping).

checks whether the window exists and is visible. On QT closing a window
merley hides it, so the common hack for checking whether a window exists

exists = cv2.getWindowProperty(.., 0) >= 0

does not work.

QPushButton was included twice.

* 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

* removed OpenGLFuncTab, now extensions are loaded internally
* renamed GlTexture -> GlTexture2D
* 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 OpenCVFindIPP.cmake script, which will look for IPP installation at CMake configuration time. First, IPPROOT environment variable will be tested, if not found script will look at default install places.
The script should support IPP from 5.3 up to 7.x versions (although tested on Windows for IPP 6.1 and IPP 7.0 versions only)

Preliminary optimization of HOG with IPP added too. Not yet quite efficient, code for cpu branch should be redesigned in order to have better performance.

fixed mouse painting in Qt bindings (to make watershed & inpaint demos work); increased the font in the detailed pixel image display.

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Qt compilation pb with OpenGL flags fixed

Fixed bug with exclusive buttons
Fixed memory leaks

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  - cvCreateOpenGLCallback: draw 3D on top of the image

bool not defined ? -> changed everything in int

 - add CV_RADIOBOX with exclusive mode

 - cvAddButton changed to match requirement
 - CV_GUI_NORMAL and CV_GUI_EXPANDED done
 - context menu with right click

 - cvAddButton done
 - All the "actions" of the toolbar are working
 - Window properties done

 - fixed icvFindTrackbar bug

 - Finished toolbar: the last icon opens an external window with the trackbars inside

 - Add toolbar
 - Clean the code
 - Window properties in progress