rm unused deterministicMovingObstacle() from GridWorld
rm unused deterministicMovingObstacle() from GridWorld

It should be reintroduced if the old gridworld benchmark from the year
2012 is reinvigorated.  The function was introduced in commit
0a50e891f1fab983aa24cff645bb895283689d59 where it is used in
benchmark/benchmark_tools.py

tulip-control/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control