trimsh->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 (4 letters namespaces):
order 0 (vertex) :vert
order 1 (edge) :edge
order 2 (triangle) :triangle
order 3 (tetrahedron) :tetrahedron
Current version uses the lib flexible search structures.
Now the comparison can be done exploiting a static uniform grid,
a hashed grid or a hierarchy of AA box.
SamplingFlags struct added
optional treatment for unreferred vertices.
Note: unref vertices are tested against unref vertices without
using the grid...it is n^2 with n number of unreferred vertices. To make it
with the grid in the proper way :
derive face and vertex from a simplexClass,
instantiate GridStaticPtr on the simplexClass template.