After #1801, the include directories are no longer added automatically,
so we should show the user how to do that.

This is the preferred style nowadays, and more consistent with the
rest of the code.

Fixes <http://answers.opencv.org/question/23997/opencv-247-cmake-includes-all-modules-even-if-i/>.

Epoch is gone; now the version component names in C++ and CMake
are consistent (except REVISION corresponds to PATCH).

The general convention is <output file name> + ".in".

This is something that should be left to the user, that's the whole
point of OpenCV_INCLUDE_DIRS.

Allow to build samples via OpenCV binaries from distribution package
(find_package with OpenCV_DIR).

Support functions from OpenCL 1.1 / OpenCL 1.2

We never set it, and libdc1394 0.9.5 is obsolete anyway - 1.0 came out
in 2004.

Note that 1.0 doesn't have the do_extra_buffering parameter.

I didn't make the status part of the version variables here, because
letters don't play too well with version comparison algorithms
(especially with CMake's, which only supports numbers).

Additional CMAKE flag WITH_WINRT added.

Now the HAVE_* macros are set in cvconfig.h. Most of them already were there,
but were nonfunctional.

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.

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.

I don't know why it didn't work for the original author, but it definitely
works now.