Several fixes and optimizations mainly of the Propagator

Ciao Benedetto, trying to produce some nTuples with Bender from Lamarr to study the PID output, I found some small bugs here and there in the Propagator algorithm and I took the opportunity to clean and polish a few things.

I think these fixes should be merged as soon as possible to avoid duplicating them. I avoid pushing directly on WIP_Lamarr only to help you with merging in case on uncomitted work.

Ciao, Lucio