[vtkusers] correct way of using VTK_MODULE_INIT with opengl2

[Ahmet Doğan]

hi,

I have swith to opengl2 for performance purposes. But when I was using 
opengl just I init rendering modules like

#define vtkRenderingCore_AUTOINIT 
4(vtkInteractionStyle,vtkRenderingFreeType,vtkRenderingFreeTypeOpenGL,vtkRenderingOpenGL)
#define vtkRenderingVolume_AUTOINIT 1(vtkRenderingVolumeOpenGL)

but after compiling vtk with opengl2 support some of them not using 
anymore than I tried to use with "autoint.h" like

#include <vtkAutoInit.h>
VTK_MODULE_INIT(vtkRenderingOpenGL2)

after that I get warning : vtkInteractorStyleSwitchBase 
(00000000026CCE00): Warning: Link to vtkInteractionStyle for default 
style selection.Thus, what is the correct initialization for 
vtkRenderingCore and vtkRenderingVolume with opengl2 backend.

Kind Regrads.
Ahmet Dogan