added METHOD_CASES, resolveq_cases_tac;
removed multi_resolveq;
improved 'tactic' method: bind thm(s) function;
consts normal :: ifex => bool
primrec
"normal(CIF b) = True"
"normal(VIF x) = True"
"normal(IF b t e) = (normal t & normal e &
(case b of CIF b => True | VIF x => True | IF x y z => False))"