generate module and scene image when running modelchain

[cdeline]

if modelchain is called from GUI, it should generate a sample image of the module and the scene for debug purposes.

[cdeline]

This process has been requested to help with reporting results and debugging the process. It's not straightforward because unfortunately objview doesn't seem to have an obvious way to run non-interactively and save an output, so I'll largely duplicate the process of objview.pl and follow the same procedure for making a scene image.

[shirubana]

@cdeline I think this was accomplished in the last release? or at least on development branch.