Integrate new module cvv: Interactive Visual Debugging of Computer Vision applications

NOTE: This pull-request corresponds to https://github.com/Itseez/opencv/pull/2531
Test compiled against current opencv 2.4 branch with gcc-4.8.

Hello OpenCV community,

as an extensive OpenCV user, I have been wishing for a utility that helps in developing and debugging computer vision code. One usually ends up writing some hacky, custom code, e.g. to more clearly show the effect of applying some filter (and tuning its parameters), which is thrown away afterwards. Reinventing the wheel over and over again.

I now had the opportunity to supervise a student assignment [1] to remedy this situation.
The result is cvv or cvvisual an interactive debugging GUI for OpenCV (https://github.com/CVVisualPSETeam/CVVisual and http://cvv.mostlynerdless.de).

The pull request integrates cvv as new module into the OpenCV build system, including a complete tutorial (with a test application you can use to give cvv a spin).

At the moment, there are visual debugging aids for many filter operations and for matchings.
Many areas of OpenCV are not yet covered, but I think a solid framework has been built with lots of useful utilities that enables to add new functionality fast and in a modular way.
I plan to add further functionality myself - instead of writing more custom code for the trash can.
Of course, my hope is that other people (hello community) will do the same, resulting in a useful tool for every OpenCV user.

Comments and discussions are highly welcome.
Please give cvv a try in your own applications and report on successes and shortcomings.

Kind regards,
Andreas Bihlmaier

[1] Credit goes to Johannes Bechberger, Erich Bretnütz, Nikolai Gaßner, Raphael Grimm, Clara Scherer and Florian Weber.