Closed - added support for building VRML2FILE from Geant4 for input to the event viewer, controlled by following configuration options:

# geant4 visualisation (not event display)
geant4_visualisation = False
visualisation_viewer = "VRML2FILE"  # only supported option
visualisation_theta = 90.
visualisation_phi = 90.
visualisation_zoom = 1.

I also added a script to append opengl bindings to geant4, but this is not officially supported because it ends in all sorts of trouble with having correct opengl library. But should work by doing something like run third_party/bash/32geant4extras.bash and add maus_opengl=1 environment variable. I test only that we make a vrml file, assume geant4 does the rest.