* move layout.h & layout.cc from relay to tvm

* change ConvertLayout in relay to bijectiveLayout->Forward/backward

* add first test case

* add LayoutAxis

* add LayoutAxis struct and compiles

* simplify BijectiveLayout rule consturct

* polish func name for Layout, move impl to .cc, remove Layout::defined(), add defined() checker

* partially add layout py support

* add layout test cases

* add doc for tvm.layout & tvm.bijective_layout

* fix lint

* fix lint

* fix layout name generation bug

* fix layout typo

* address comments and add topi.layout_transform

* layout.h->data_layout.h, test_lang_layout.py->test_lang_data_layout.py

* check in

* lint

* cleanup

* Update util.py

tshape.strip('()[]').split(',') will make a list ['1001',''] but the empty one isn't needed.

Recent pylint introduced support for the useless-return diagnostic.
This patch remove the useless returns.

* [DOC] CoreML frontend tutorial

* Update tutorials/frontend/from_coreml.py

Co-Authored-By: kazum <morita.kazutaka@lab.ntt.co.jp>

* Update tutorials/frontend/from_coreml.py

Co-Authored-By: kazum <morita.kazutaka@lab.ntt.co.jp>

* Addressed comments and added the original author

* Add CONCATENATION to tflite frontend

* fix typo

* Fix codestyle

* Fix code style

* simplify convert map

* Update

[Relay] fix error in ANF (too agressively inline atomic expression and create free variable). (#2665)

* i think it works for now?

* fix lint

* fix 2/3 compat

* fix py2 again

* fine, i gave up

* Add arange op

* Update docs

* Fix bug

* add sanity check in relay and mxnet frontend mapping

* lint

* nits

* pylint

* don't allow empty output from arange

* Remove empty test for arange

* Fix bug and update doc

Recent pylint warngs about import renames with no effect.  Remove
them.

* check in

* fix typo

* fix typo

* change message

* change message

* typo

* lint