Structured edge detection & State-of-the-art image inpainting

This pull request is the part of my Google Summer of Code work. Here I implemented fast edge detection using structured random forests which was recently proposed by Piotr Dollar, state-of-the-art image inpainting algorithm proposed by Kaiming He, and two simple image processing techniques: dct-based image denoising, and simple color balance.

This pull request is clone of the https://github.com/Itseez/opencv_contrib/pull/25