Need a way to extract states of models to transform to experimental formats

[harisorgn]

This is a feature request particularly useful for the experimental/clinical tutorials.

My initial plan is to add hook functions into run_experiment! to extract states of the Cortico-Striatal (CS) model every trial to then create LFP averages out of them and consequently BOLD-like data via HRF convolution.

In the long run though we should consider "observable" Bloxs that when attached to normal Bloxs output a plot of transformed states that is relevant to experimental and clinical people (like the CS model example above).