* Add shapeof op in topi

* Add relay shape_of op

* Add constant folding for shape_of

* Allow shape op to specify dtype

* Add mxnet converter for shape_array

* lint

* lint

* Add doc

* start adding reverse

* reverse updated

* reverse uses topi::flip

* typo fixed

* comment addressed

* exp simplified

* tile and repeat operator added in rely

* fix pylint

* fix make warnings

* comments addressed

* fix lint error

* comment addressed

* add stack op frontend

* concate moved

* topi stack added

* stack added

* fix stack bugs and tested

* conv2d alterlayout udpated for relay

* fix pylint

* fix cmake warnings

* cmake warnings fixed

* 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

* Enable reverse in reshape

* Fix lint and typo

* Put reverse_reshape into a separate op

* Fix pylint

* [QUANTIZE] Quantization implementation.

* Update.

* Update.

* Update.

* Update.

* [RELAY] Finish alter op pass

* [RELAY] AlterOpLayout Pass

* fix broadcast operators

* fix broadcast operators

* fix broadcast operators

* Support concatenate

* address comments

* address comments

* add comments

* rebase

* [RELAY][PASS] FoldScaleAxis Forward

* Introduce helper function type_as

* Update per review comment

* Fix according to comments

* [RELAY] BiasAdd, MLP, Resnet testing

* fix review comments