Issue 3580: Replace unwarranted uses of map with for-each and other Scheme cleanups

Issue 3580: Replace unwarranted uses of map with for-each and other Scheme cleanups

Note that some uses of map actually relied on execution order (namely
expecting map to behave like map-in-order) and thus were not just
inelegant because of the side effect.  There are also some other
mostly trivial simplification of Scheme constructs.