Completed step of the integrator.
callEventUpdate = fmiCompletedIntegratorStep(instance)
tlist, an instance of a model.
boolean, callEventUpdate = %t or %f.
fmiCompletedIntegratorStep is the function which must be called after every completed
step of the integrator. If the function returns with callEventUpdate = true, then the function fmiEventUpdate must be called,
otherwise, no action is needed.