Fix compilation on Visual Studio
Fix compilation on Visual Studio

For VTK < 6.3.0, vtkRenderingFreeTypeOpenGL is required by Visual Studio

ddao/CTK,commontk/CTK,CJGoch/CTK,commontk/CTK,commontk/CTK,151706061/CTK,SINTEFMedtek/CTK,sankhesh/CTK,151706061/CTK,commontk/CTK,CJGoch/CTK,ddao/CTK,sankhesh/CTK,SINTEFMedtek/CTK,AndreasFetzer/CTK,AndreasFetzer/CTK,SINTEFMedtek/CTK,naucoin/CTK,naucoin/CTK,jcfr/CTK,CJGoch/CTK,sankhesh/CTK,SINTEFMedtek/CTK,jcfr/CTK,naucoin/CTK,Sardge/CTK,AndreasFetzer/CTK,Sardge/CTK,Sardge/CTK,jcfr/CTK,SINTEFMedtek/CTK,ddao/CTK,AndreasFetzer/CTK,151706061/CTK,Sardge/CTK,jcfr/CTK,sankhesh/CTK,CJGoch/CTK,ddao/CTK,CJGoch/CTK,jcfr/CTK,naucoin/CTK,151706061/CTK,151706061/CTK