Updated the SeatingChart toString() method.

Columns still don't quite align perfectly due to difference in size
between an empty seat ([ ]) and a filled seat ([X]), and I might see if
I can get it even better, but if not, it should print out pretty good
now!!!

Take a look at it and let me know what you think and/or if you have a
better solution as to how to fix this!

I could put a different letter in empty seats to try to make them the
same size as filled seats and that way they would hopefully line up
better! What do you guys think?