new interface: using id() to identify algorithm types
adapted to algorith factory changes
algorithm type -> id
adapted to new input/output parameter names (mesh instead of default)
code cleanup
added support for extracting volumetric hole points (tetrahedron 3D and triangle 2D meshes)
added support for holes in PLC
added hole points output
added example for extracting hull with hole points
new example mesh: cube with cube hole and cube inside the hole
updated to rename (extract_hull -> extract_boundary)
rename: extract_hull -> extract_boundary, moved extract_hole_points to ViennaMesh (interface currently too unstable for ViennaGrid)