New file with a Plane class (data structure), which collections all available information
for a plane.
Created a planar data structure, which is now filled.
Must look into various conventions for canonical form.
I also store HSV average colors.

There is probably still a segmentation error. Do not know why.
Copied various plane-related methods to plane.* (Plane class), so that I may
reuse functionality common to segment and multi_plane_segmentation.
Some refactoring of multi_plane_segmentation.cpp .
I now process two input files files when running multi plane segmentation of organized
clouds.
Added tons of routines to plane.hpp and plane.cpp, which used to be in multi_plane_segmentation.hp . Part of refactoring process. I have still not removed the routines from multi_plane_segmentation. This will also help consolidate segment.

Code compiles on the mac.