Pipe the current triangulation to Geomview for display. Much of this is based on Ken Brakke's Surface Evolver.
int GeomviewDisplayTriangulation ( MPI_Comm comm, PetscScalar* minmax, char* name )
First, this creates global and local vectors for all of the triangle vertices.
It then gathers (``scatters'') all vertex data to processor zero,
and puts them in an array.
Finally, it sends everything to Geomview,
and cleans up the mess, resetting the number of triangles to zero.