Add support for multiple runs

[agarny]

Right now, using our Interactive view, a user can run only one simulation and that simulation gets updated on the fly whenever the user modify a model parameter.

Here, we want the simulation to be run whenever the user decides to run it. This means that the user:

• can modify one or several model parameters, track those modifications, and then run the corresponding simulation.
• have multiple runs with different model modifications.
• decide which run(s) to show.