Upgrade LCLS backend

[daurer]

The python interface to psana made some progress over the past year, which is currently not integrated into our LCLS backend.

Most important upgrade would be the psana Detector class that allows for customized detector corrections and makes the ugly psana config file obsolet.

We have also had problems recently with some detector sources (in-line microscopes, etc...). We ended up hard-coding the source depending on the experiment. There should be a more general way to deal with different data (varying in shape, dtype) showing up on same/similar source ids.

Is there any other changes to be made in the LCLS backend?