Main function in pipeline.py and distribution_maker.py broken

[JanWeldert]

The main function in pipeline.py is out-of-date. It tries to give pipeline.get_outputs() an idx parameter which is not supported anymore.

The main function in distribution_maker.py returns an error if run with the return-sum argument (and the example pipeline).

Potentially need to check other main functions in pisa/core too.

[thehrh]

There is also a related fixme note in setup.py (since #812).

[JanWeldert]

Right, there is also a comment about it in the main function in pipeline.py itself.