[3rd attempt] fixed HOGDescriptor::detectMultiScale() to group weights as well as ROIs
Reverted back to the previous method where a public method groupRectangles was added to HOGDescriptor to take care of ROI and weight grouping
Added spacing in a nested template argument list.
added documentation for OpenGL interoperability
PvAPI support on Windows with MinGW (PR #1038 applied to the branch 2.4)
added handling of camera parameters estimation errors (#3122)
added 'cmath' include
fixed Windows build
removed trailing whitespaces causing warnings
updated docs
fixed include for Windows
fixed docs
Improve FPS on black and white Ximea cameras
Remove HAVE_CVCONFIG_H - it's always defined.
Deleted a bunch of unused configuration macros.
Removed a few more unused configuration macros.

I've left HAVE_LIBPTHREAD as a CMake variable, since TBB's build depends on it.

Some macros in internal.hpp depended on HAVE_ALLOCA_H, but they were, in turn,
unused, so I've just deleted them all.
Refactored detecting several Apple-related technologies.

Now the HAVE_* macros are set using cvconfig.h. Previously most
of them already were there, but were always undefined. One,
HAVE_COCOA, I had to add.

This also makes the CMake code more consistent; now, WITH_* variables
are always checked in cmake/*, while HAVE_* variables are checked in
modules/highgui/CMakeLists.txt.
Refactored image format library finding logic.

Now the HAVE_* macros are set in cvconfig.h. Most of them already were there,
but were nonfunctional.
Removed unused NEW_FFMPEG macro.
Removed the HAVE_LRINT macro, which is never set.