PLT Redex definition of STG as per fast curry paper

For those of you who aren't following the commit list, I've just pushed a PLT Redex http://redex.racket-lang.org/ definition for an STG-like language as was defined in the fast curry paper. This language is *not* STG. The hope is that this will be a good starting point for actually formalizing STG as it exists today. I've included a hefty comment block at the top of the development summarizing ways in which this could be improved. Take a look if you're interested! Cheers, Edward