0.8.16.1: reader ANSI fixes

0.8.16.1: reader ANSI fixes
           * Return primary value NIL for various READ-FOO when
              *READ-SUPPRESS* is NIL.
           * Eof-error-p in READ-FROM-STRING defaults true.

          HEALTH WARNING: These changes will probably break Slime,
           or at least parts thereof. Slime patch forthcoming.