trimesh->tri
clean up of some namespaces to comply the following naming:
Complexes (3 letters namespaces):
order 0 (point cloud ) :vrt
order 1 (edge meshes) :edg
order 2 (triangle meshes) :tri
order 3 (triangle meshes) :tet
Simplexes (extended namespaces):
order 0 (vertex) :vertex
order 1 (edge) :edge
order 2 (triangle) :triangle (temporarily it remains "face")
order 3 (tetrahedron) :tetrahedron
ganovelli
Paolo Cignoni
Nico Pietroni