The video(4) driver provides a Video4Linux2 compatible API for
various video peripherals. This patch propagates HAVE_VIDEOIO if
the sys/videoio.h include file is found, which is the signature of
video(4).

This reverts commit 2e7656db.

This reverts commit 36135fc5.

Window-related functions is guarded from calls from application code.
Old implementations with "no-gui" exception are stell compiled and linked to OpenCV library for binary compatibility.

fixed 2 build problems on MacOSX (highgui with ffmpeg, opencv_world); added macro CV_INIT_ALGORITHM for simpler algorithm registration (ticket #1876)

Shortened CMake script for opencv_world. Fixed opencv_world link with non-Visual Studio generators on Windows.

added opencv_world module that combines all the other [selected by user] OpenCV modules, except for opencv_python and opencv_gpu.

get back to single-version ffmpeg wrapper (no more v2); make sure the library builds and the tests pass on Ubuntu 10.04 that includes pretty old version of ffmpeg

added version number to opencv_ffmpeg dlls (it's added only when dll copied to the bin directory); it resolves #1827