level limit hack: prevent calling ki in term index

We do not call ki for well-kindedness checking from type inference of t1
in type (T {t1}) where (t0 :: T {t1}). That is, when T {t1} is
an inferred type of some t0. We would normally call ki to check
well kindedness to for terms at the outermost level (i.e. global definitions).

* WARNING: this hack is not proved correct, just having leap of faith for now

Now, path.miniax only(?) use 1.x GB memory, which is much better than
using up more than 3.5 GB memory and amost freezing my laptop.