Repulsive force parameters

[chraibi]

In JuPedSim all models have some kind of repulsive effects on agents.
For instance, GCFM and SFM have repulsive forces.

Depending on the scenario and density, these forces may grow big and cause agents being pushed out of the boundaries of the simulation.

So, with increasing number of agents, the strength of the repulsive force should be decreased and vis versa.

JuPedSim does not implement any safe-guards against this behavior. So simulations just stop.