move nadf.schema as it depends on lastModifiedBy

Small preparation for applying tighter semantics to operational attributes.

Passes last test (empty value); also passes many of the invalid DN tests if liberal parsing is allowed

fix non-printable flag detection; improve dn test (passes all but last in http://www.openldap.org/ietf/ldapbis/dn.txt)

to scan a berval in-place.

No visible impact from these changes.

Intended to be used instead of ch_malloc() and friends.
See comment.