Lccp

This pull-request is part of the GSOC 2014 project of Markus Schoeler (Automated benchmark generation for object-part segmentation).

It contains an implementation of the lccp segmentation published in:
S. C. Stein, M. Schoeler, J. Papon, F. Woergoetter
Object Partitioning using Local Convexity
In Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition (CVPR) 2014 

In addition, it contains an example "example_lccp_segmentation.cpp" which shows how to use the lccp segmentation.
If there is an alternative, and it's actually useful, then we should expose it to the user in some way other than through commented code. This file will be installed to e.g. `/usr/local/pcl/include`, and users are not supposed to dig there and uncomment stuff.