0.8.3.84:

0.8.3.84:
        * fix bug reported by Nicodemus Siivola:
        ... FIND-RESULT-TYPE: ignore uses in deleted blocks/functions;
        ... DELETE-LAMBDA: work with :OPTIONAL;
        * DELETE-BLOCK: when deleting ENTRY, delete it from
          LAMBDA-ENTRIES and delete all its EXITs.
        * add DERIVE-TYPE optimizer for ISQRT (thanks to Robert
          E. Brown).