Version 0.4

RBuilder now generates several different executable R scripts - one for
each function in a given package.

I also added some command-line interaction to help determine argument
types for each function. It's a bit clunky at the moment, but this will
allow the code to generate R scripts in their entirety without forcing
the user to edit them. Currently, the program doesn't use the argument
types for anything; that will be changed in the next update.

Finally, I removed all dependence on the given package's reference
manual.