ENH:
Added functionality to vtkAMRBox that will facilitate construction of block structured AMR datasets. Added initializers to vtkUniformGrid that take vtkAMRBox as an argument. Added a public Set/Get to vtkAMRBox interface so that member variables could be made private. These public members are left public for now for backward compatibility. Updated all VTK/PV classes that use vtkAMRBox to use the new public interface instead of accessing the public mebers directly. Added a test for the vtkAMRBox.