Updating changed models' code #51

If you change a child model's code, you currently need to reload the model, thus losing its current state.

I am wondering if we can update the code in models that have already been loaded. It seems to be possible in main NetLogo (if you set up a model, run it a bit, change one of its procedures, and run it again, it will run with the changed procedure). So it seems that you can change the code of a model without wiping its state.

Can we somehow transfer that feature to LevelSpace?

Related to #43