Add Camera Gizmo Widget To vtkPVRenderView

• Use 2nd generation widget framework
• Synchronizes gizmo orientation with parent renderer's camera
• Interactively jump to specific view point (+/-X, +/-Y, +/-Z)
• Drag gizmo handles to orient camera.

For now, this gizmo is hidden by default in vtkPVRenderView. To show it, hide the orientation axes. Click on this button.

This will hide the orientation axes and display the gizmo.