resolve_inc_tyvars: back to old behavior before 0fa3b456a267 where types of equal Vars are *not* unified -- recover last example in src/HOL/Metis_Examples/Clausification.thy;

more precise "incremented" indication, which might be relevant in corner cases, e.g. instantiation of leading to vars with different types (which is a potential problem nonetheless);

tuned signature -- more explicit flags for low-level Thm.bicompose;

unify types of schematic variables in non-lifted case (i.e. "compose variants") -- allow schematic polymorphism, without revisiting HO-unification;