Adding a prompt command.

I decided to add a prompt command to the JustinTime Interpreter because
I was bored.  I don't know how effectively I did it, you'll probably
end up changing it. :P  It does work though.
Increased Window Size

I made the window ever so slightly bigger so the prompt text would be a
bit further from our last line of text.
Realized a Better way

I improved the way the Prompt is replaced to make more sense, but now
I'm trying to figure out how to make it handle multiple commands like
go and prompt in one thing.
Bug Fix

I managed to fix it so that it will properly work if you use both a
prompt command and a go command together.