number of step of the simulation

When I try to do step by step simulation, I get a problems.

I propose to change the line 391 of simulator file : 

n_steps = int(math.ceil(self.simulation_length / self.integrator.dt))

by the following line :

n_steps = numpy.rint(self.simulation_length / self.integrator.dt).astype(int)

The change is to round at the nearest interger and not the highest integer.
This modification avoids error when the floating number is convert to integer.