folder structure
Source files added
documentation and code formating on ppf_match_3d.hpp
some more documentation
code refactor
Some more documentation and the latest updates.
Merge branch 'master' of https://github.com/tolgabirdal/opencv_contrib into add_surface_matching_gsoc

Conflicts:
	modules/surface_matching/include/opencv2/icp.hpp
	modules/surface_matching/include/opencv2/ppf_match_3d.hpp
	modules/surface_matching/include/opencv2/surface_matching/pose_3d.hpp
	modules/surface_matching/include/opencv2/surface_matching/ppf_helpers.hpp
	modules/surface_matching/include/opencv2/surface_matching/t_hash_int.hpp
	modules/surface_matching/src/icp.cpp
	modules/surface_matching/src/pose_3d.cpp
	modules/surface_matching/src/ppf_helpers.cpp
	modules/surface_matching/src/ppf_match_3d.cpp
	modules/surface_matching/src/t_hash_int.cpp