Interactive Shell

So, I assume you aren't going to want to incorporate this, but I suggest that you at least try it. I facebooked you a short demo video of how it works, but it has been greatly improved since then. A couple of things which haven't quite been added yet:
~~-Functions. They would work if Gunderscript let you define functions inside functions. I really shouldn't expect that of Gunderscript, so tomorrow I should be able to work around that and get functions working in the shell.~~
-One of the main things the shell has to do is keep parentheses, brackets, and braces balanced. Right now it does a simple count, so if your code has one of those symbols that doesn't actually contribute to the count (eg. sys_print("(}[")), then the count could get all messed up. This might be kind of tricky because it would actually mean going through the lines and counting quotation marks, along with escape characters and whatnot. Should not be a problem in most cases, especially because most of the time people will use these symbols in strings, they will be properly closed anyways (unless someone tries to print out some emoticons or something).
~~-If you save what you have been running to a file, the print statements will be commented out. Easy fix, just haven't gotten around to it yet.~~