Support qt5 2017 08 11 r26241

Created by: jcfr

This PR will add support for Qt5 and VTK8 while allowing to build using Qt4 and VTK7 (the detault).

I plan on integrating later tonight and I will follow up tomorrow.

Note that the VTK build tree is named VTK8 but it contain either VTK7 or VTK8.