Reducing output file memory

[valeriaRaffuzzi]

At the moment, when writing the output file, all the tallies print their results in a unique charTape instance, and this gets written in the output file at once.

This approach is memory expensive when there's a lot of tallies, since the memory taken by the tallies gets duplicated when the results are written in the charTape. It would be more memory efficient to write the charTape into the output file after each tally is printed, and then clear the charTape. This would avoid long memory-intensive tapes.