* 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

* [Tutorial][Frontend] move from_keras tutorial to frontend

* remove tutorial/nnvm/from_keras.py

* add a relay pass to count #macs of a model

* remove unnecessary includes

* fix end-of-file issues

* address review comments

* remove test resnet

* address more review comments

* use data layout string to locate the input channel

* fix bug in conv 2d output tensor checking

* C must exist

Thanks @hlu1 and @tqchen, this is now merged.

* Add eager simplication for FloatImm

* fix

* fix lint

* Fix gcc warning

* fix

* Add test case