Fix PyVTKTemplate dict compatibility methods.
Fix PyVTKTemplate dict compatibility methods.

The get() method was incorrectly implemented and segfaulted.  Also,
with py3k, the keys() method returned a special object instead of
a plain list, and this caused the wrapping to fail.

gram526/VTK,mspark93/VTK,mspark93/VTK,gram526/VTK,SimVascular/VTK,sumedhasingla/VTK,SimVascular/VTK,keithroe/vtkoptix,sumedhasingla/VTK,keithroe/vtkoptix,sankhesh/VTK,jmerkow/VTK,jmerkow/VTK,sumedhasingla/VTK,gram526/VTK,jmerkow/VTK,keithroe/vtkoptix,sankhesh/VTK,SimVascular/VTK,mspark93/VTK,keithroe/vtkoptix,mspark93/VTK,jmerkow/VTK,keithroe/vtkoptix,SimVascular/VTK,SimVascular/VTK,sankhesh/VTK,SimVascular/VTK,jmerkow/VTK,keithroe/vtkoptix,gram526/VTK,jmerkow/VTK,sankhesh/VTK,sankhesh/VTK,sankhesh/VTK,keithroe/vtkoptix,sumedhasingla/VTK,mspark93/VTK,keithroe/vtkoptix,sumedhasingla/VTK,sumedhasingla/VTK,gram526/VTK,jmerkow/VTK,gram526/VTK,mspark93/VTK,gram526/VTK,SimVascular/VTK,SimVascular/VTK,jmerkow/VTK,sankhesh/VTK,sumedhasingla/VTK,sumedhasingla/VTK,gram526/VTK,sankhesh/VTK,mspark93/VTK,mspark93/VTK