* Set split node's range to minimum of ext and split factor or split nparts, but only when PassDownDomain is called with allow_missing == false, i.e. by InferBound. Add a helper PassUpThreadBinding() to get a map telling whether an IterVar has at least one leaf IterVar deriving from it binding to a thread. Add two unit tests.
* Enhance LoopVectorizer for vectorizing by 0. Found at least one case from testtopi/tests/python/test_topi_transform.py::test_tile.
* Revert changes vectorize_loop.cc; when parent's ext is zero, set split's range to the factor or nparts.
* Update with comments.
* Refactor the ext tightening predicate.
* Fix reference types.
* Integrate tvm.te changes.
* Trivial comment change to trigger CI.
* Trivial comment correction to trigger testing.
