Added methods to LSM to allow for smaller sized levelscenes to be stored - currently using size 11 (as Mario can only interact with the nearest 5 squares in any direction)

Added safety check when deleting the .ser file to make sure it exists first - otherwise we ended up in an infinite loop.
Fixed bugs with storing LSMs:
* the distance travelled right was negative (in the reward) due to a sign error
* storing the reward of the previous set of actions/levelscene under this set of actions/levelscene