improved O.stopAtTime
improving MR !487 (merged) scene->stopAtTime is set to -1 after pusing (otherwise the simulation is stopped immediatelly after O.run()) scene->stopAtIter the same to be consistent
improving MR !487 (merged) scene->stopAtTime is set to -1 after pusing (otherwise the simulation is stopped immediatelly after O.run()) scene->stopAtIter the same to be consistent