Refactor on Triangle neigbor getter methods:
* small enhancement of getter of vertex opposite from edge
* minor optimization for isDirectNeighbor()
Small refactor of region boundary handling:
* done at the level of the region boundary updater and at the level of the
region grower (based the implementation on edges neighbor parsing)
Added statistical functionality for Model:
* handling of statistics of curvature estimations for CAD model vertices
* mean, gaussian curvature properties and getter and setter methods
implemented
* average and variance of curvature scalar data points added along getter
and setters
Added empty constructor and copy constructor:
* implemented copy constructor to perform copies of Appearance objects for
newly added triangles in the knowrob_mesh_reasoning package