This has no bearing on compilation, but it makes them show up in IDEs.

We don't really need it, it makes the code longer, and it can lead to
inconsistent paths when OpenCV is itself inside a symlink.

see: http://code.opencv.org/issues/2897

The order of the 2 conditions is really important, as every MATCHES
operator sets ${CMAKE_MATCH_1}, which is needed inside the condition
block. Ideally, this should be done using a single regex with a
negative forward lookahead, but CMake doesn't seem to support this

Backport from master.

All tests passed!

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

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

Sometimes information about dependencies causing disabling were loosed and it
was not possible to correctly display these dependencies in status report

This suppresses "unused variable" CMake warning when user explicilty disables
module unavailable in selected configuration

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.

Improved Android SDK search, fixed some bugs.