Pov-ray export

I’ve finished fixing what I could in the pov-ray export, mostly the camera and
Remains TODO (just FYI; I can’t do it as eigen2 is calling me back):

  • other primitives (quads, sectors, text…)
  • nicer dialog (I’m ignorant for GUI stuff). I added a QInputDialog for the
    aspect ratio but it could use becoming a real dialog, its text should have
    automatic formatting instead of the \n that I had to put, and it would be
    useful to have a QLabel giving an example pov-ray command-line with
    dimensions matching the current aspect ratio (like +H1000
    +W<1000*aspectRatio>) (following the aspectratio entered by the user in the
    QLineEdit) and AntiAliasing=on so that users can quickly get a satisfactory