Basic Hole filling

[cignoni]

Hole filling: Following the basic pieces in library provide a filter that fills a hole and, after the closure of the hole it performs some remeshing in order to improve the generated triangulation. Remeshing should be done by iterating refinement, smoothing and edge-flipping until certain conditions on the generated triangles are met. Eventually at the end displace the vertex of the surface in order to ensure better boundary continuity.