Added padding around the debug screen, more debug improvements, NullPointerException upon launch bug fixed.

Not a good idea to use the object you’re constructing is it? The game
wouldn’t launch correctly because EnterText() was accessing
MathQuizGame.frame, which was at the time, when EnterText() was called,
being initialized, and the program threw a NullPointerException.

This bug was related to my conversion to non-static fields in
MathQuizGame.
Fixed argument parsing for custom difficulty level.

parseArgs() would return something crazy if the command does’t start
with a “/”. It still does, but I fixed the code in
MathQuizGame.somethingHappened() so that the parser thinks that the
text “c 10 0 +-x 2” is actually “/c 10 0 +-x 2” so it will return
{“10”,”0”,”+-x”,”2”}.

Also, it is easy to register a command into the command parser, so that
it is recognized as a command. I did this for my sake because I did not
want to keep writing if statements every time I added a new command.
Fixed /help command and /clear command

With the new command structure, all the commands broke. This was
somewhat intentional, because when refactoring everything, I knew that
I would have to re-implement the commands. So far, /help, /clear,
/debug, /say, /history, /quit, /restart, /setsize, and /setfont work.
Update private.xml