added METHOD_CASES, resolveq_cases_tac;
removed multi_resolveq;
improved 'tactic' method: bind thm(s) function;
Sep2 = Main +
consts sep :: 'a list => 'a => 'a list
recdef sep "measure length"
"sep (x#y#zs) = (%a. x # a # sep zs a)"
"sep xs = (%a. xs)"
end