using a separate sexp_free_list type, so we don't need the overhead of the sexp tag and should thus fit in any aligned block on 64bit architectures.  this also removes a lot of ugly casts, making the code more readable.
using a separate sexp_free_list type, so we don't need the
overhead of the sexp tag and should thus fit in any aligned
block on 64bit architectures.  this also removes a lot of
ugly casts, making the code more readable.

traviscross/chibi-scheme,traviscross/chibi-scheme,traviscross/chibi-scheme,traviscross/chibi-scheme