Set light transform matrix irrespective of light type

Change-Id: Ib94073e1139d4ef373d5322e6beb9a593e3986e4
ENH: Added test for vtkRenderingExternal

TestGLUTRenderWindow demonstrates the use of the
vtkRenderingExternal module by rendering VTK objects in a GLUT
window.

Change-Id: I8bbbdc4a05b335b105da971217d0f5a31891b5a9