adjust compiler-macro expansion and lambda-list parsing

adjust compiler-macro expansion and lambda-list parsing

 * Don't convert errors during compiler-macro expansion into runtime
   PROGRAM-ERRORs: signal a compile-time warning, and simply decline to expand
   the compiler-macro.

   This lives in CAREFUL-EXPAND-MACRO.

 * Make compiler not expand compiler-macros if there are arguments in keyword
   positions that are not self-evaluating constant symbols.

   This lives in two places:

    (1) VERIFY-KEYWORDS signals a COMPILER-MACRO-KEYWORD-PROBLEM when it
        encounters either an unknown keyword or anything except a
        self-evaluating symbol in a keyword position when parsing
        compiler-macro keywords.

    (2) IR1-CONVERT-FUNCTOID handles this condition by unwinding from the
        compiler-macro expansion, printing a note about the problem, and
        returning the original form.

    Calling COMPILER-MACRO-FUNCTION directly behaves exactly as before, for
    both good and ill: good in the sense that it is compliant, ill in the
    sense that doing things that way may expand things the compiler would
    decline to expand:

      (define-compiler-macro foo (&key ((a ax) t)) (format nil "a=~S" ax))

    The compiler would refuse to expand (foo a 42) unless

      (defconstant a 'a)

    had been done beforehand, but calling the COMPILER-MACRO-FUNCTION directly
    would expand it even without that -- as the spec unfortuntely requires.