ProtGraph might not generate files while called through Python

[Dominik Lux]

The calls (like in the functional tests) might not work properly.

Here is an example:

        args = protgraph.parse_args([] + self.procs_num + self.example_files)
        protgraph.prot_graph(**args)

[Dominik Lux]

This cannot be reproduced on an linux environment, keeping it open, since other OSes might have this issue