ENH: Restore Common/DataModel Cxx tests
Restore Cxx tests that were not ported to vtk6.
Minor cleanup on the tests.
CellLocator2 removed because it was redundant with CellLocaotr (now TestCellLocator).
Restore Cxx tests that were not ported to vtk6.
Minor cleanup on the tests.
CellLocator2 removed because it was redundant with CellLocaotr (now TestCellLocator).