Initial inclusion of a LUCID implementation

OpenCV currently contains at least two nonfree programs that can be used for construction of image descriptors (SURF and SIFT, to my knowledge). I offer a free adaptation of the Locally Uniform Comparison Image Descriptor (Ziegler, Andrew, Eric Christiansen, David Kriegman, and Serge J. Belongie. "Locally uniform comparison image descriptor." In Advances in Neural Information Processing Systems, pp. 1-9. 2012.), under a license compatible to GPL, hoping to provide one additional free program to OpenCV that allows descriptor construction, such that developers and users need not sacrifice the freedom of their computer for completion of this task.

This is my first contribution to OpenCV. I attempted to adhere to coding standards where required as instructed by your style guide. This initial functionality includes the construction of descriptors, as well as exposing a separable box filter blur that the developer may use on images independently. I have also included a simple test case, sample code and required documentation. This code compiles and the test succeeds on my GNU/Linux operating system, but is currently untested on other platforms. In accordance with your contribution guide, this commit does not include additional feature matching functionality that would be compatible with this image descriptor, as is stated that PRs should focus on one issue at a time. Please don't hesitate to point out in which places, if any, the code is not yet suitable for inclusion into OpenCV, and I will attempt to rectify it in a timely manner.