number of tiles
caret:	numTiles	TopologyFile->getNumberOfTiles
vtk:	cells->GetNumberOfCells()
mni:	polygon->n_items

nodes in coordinate file or points in topology file
caret: 	numCoords	coordinates.getNumberOfCoordinates
caret:	numNodes	TopologyFile->getNumberOfNodes
vtk:	numPoints	vtkPolyData->GetNumberOfPoints
mni:	polygon->n_points
