Original commit message from Mike Sperber:
Subject: Add implementation of FOR-EACH to SRFI-1
This was missing from Olin's reference implementation.
Note that currently, the native versions of MAP and FOR-EACH already
implement the extended semantics specified by SRFI 1. However, we
might want to enforce the R5RS restrictions to MAP and FOR-EACH at
some time in the future, so it still makes sense to have separate
implementations in SRFI 1.