[RIF][FLD][PRD] Negation Framework Capturing Inflationary Negation

This follows recent discussions about negation in PRD,
here called 'Nio' (Negation inflationary operator).

The FLD EBNF at
http://www.w3.org/2005/rules/wiki/FLD#EBNF_Grammar_for_the_Presentation_
Syntax_of_RIF-FLD
could be extended for 'Nio' and abstract

  FORMULA        ::= . . .
                     IRIMETA? 'Neg' FORMULA |
                     IRIMETA? 'Naf' FORMULA |
                     IRIMETA? 'Nio' FORMULA |
                     . . .
to

  FORMULA        ::= . . .
                     IRIMETA? NEGATOR FORMULA |
                     . . .
  NEGATOR        ::= 'Neg' | 'Naf' | 'Nio' | KBRDSTRING

paralleling similar abstractions we did for the
(binary) CONNECTIVEs and for the QUANTIFIERs.

-- Harold


---------
PS: KBRDSTRING is FLD's handle for extensions.