Decide what to do with options_.particles.pruning
I am having trouble with the options_.particles.pruning-option. It is used within the particle filter routines, but currently not inherited for the use of simult_ in e.g. non_linear_dsge_likelihood or irf.m. I actually don't see why we need that as a separate option of particles. I would prefer to have options_.pruning and have particles rely on it. Or to stay within the module-logic, have options_.pruning inherit options_.particles.pruning.