This removes the need to use the ES `arguments' reference. Not only is this
what we want to do, but it's _necessary_---the next commit will introduce
environments, and wrapping procedures in lambdas breaks the `arguments'
reference in each of these cases.
Note that fold and map can now be written in Rebirth Lisp, but I'm just
leaving them alone for now.
* build-aux/bootstrap/rebirth.scm
(append, string-append, +, -, map): Use define cdr in place of ES
`arguments'.