Two functions for smoothing/denoising of triangular meshes

2 functions to smooth noisy triangular meshes: Mean face normal filtering, Laplace flow filtering

Part 1)
Mean face normal filter for smoothing/denoising triangular meshes

Reference:
1) Yagou, Belayev, Ohtake (2002) Mesh smoothing via Mean and Median Filtering applied to face Normals, PGMP - Theory and Applications
2) Zhang and Hamza, (2006) Vertex-based anisotropic smoothing of 3D mesh data, IEEE CCECE
Acknowledgement:
Q. Fang: iso2mesh (http://iso2mesh.sf.net)

Input: xyz <nx3> vertex coordinates
t <mx3> triangulation index array
Output: xyzn <nx3> updates vertex coordinates

Part 2)
Laplace flow mesh smoothing for vertex ring
Reference: 1) Zhang and Hamza, (2006) Vertex-based anisotropic smoothing of
3D mesh data, IEEE CCECE
Acknowledgement:
Q. Fang: iso2mesh (http://iso2mesh.sf.net)
Input: xyz <nx3> vertex coordinates
t <mx3> triangulation index array
Output: xyzn <nx3> updates vertex coordinates