* 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

* nms data race solved

* tst_topi_vision reference results are gonna be updated in PR #2353

* proposal nms_ir updated

* alter_op_layout for x86

* cleanup

* cleanup

* fix lint

* fix lint

* fix lint

* fix lint

* change support level

* change other support levels

* check in

* update build and run

* First pass on ADTs

* Add doc string for tag field

* Visit constructors in TypeVisitor for TypeData

* Add to description of type call

* Add type call to type solving and unification

* Make type mutator for typecall consistent with others (only create new node if there's a change)

* Ensure kindchecking can handle type calls and typedata

* Fix bad nesting in module constructor

* Correctly construct call in typecall test

* Add call override for ordinary vars (do we want this?)

* Remove generalization hack from type inference because it was breaking ADT constructors

* Check that there are no free type vars in exprs after inferring type

* Free var checks need module because of ADT constructors

* Typecall test can't have unbound type var, make it global

* Uncomment tmap test and remove comments about failing to infer ret type; those work now

* Put in dummy visits for ADTs in graph runtime codegen to placate pylint

* Fix Relay type infer test module constructor

* Mark override for TypeCallNode in type solver

* Ensure free vars check treats patern vars as bound

* Run interpreter in more ADT test cases

* Refactor kind check to return the kind, like typechecking

* Fix invalid typecall in test

* Add kind check to type inference, do not use nulls in func_type_annotation()!

* Redundant whitespace

* Make TypeData a separate kind

* Make ADT handles a separate kind too, document calling convention better

* Remove nats and tree from prelude, move to test, document prelude

* Restore and document nat and tree to prelude, add more tree tests

* Add alpha equality tests for match cases, fix variable binding bug

* Add more kind check tests for ADTs

* Add more tests for finding free or bound vars in match exprs

* Add unification tests for type call

* Update main() for alpha equality tests

* Add simple type inference test cases for match exprs and ADT constructors

* Add more ADT interpreter tests

* Allow incomplete types when typechecking match cases

* Type inference for pattern vars should use the type annotation if it's there

* Two more specific test cases for ADT matching

* Add option ADT to prelude

* Fix broken reference to kind enum

* Fix rebase snags

* Do not attach checked types to constructors

* More docstrings for module fields

* Use proper wrapper for indexing into module type data

* checked_type for constructors is not populated

* Expand type call docstring

* Rename PatternConstructor con field

* Use error reporter for pattern constructor case

* Condense error reporting in kind check, use error reporter

* Expand docstrings and rename ADT fields

* Rename 'option' ADT to 'optional' for consistency with Python

* Add various list iterators and utility functions to prelude

* Add smoke tests for new iterators in prelude

* Add concat to prelude

* Add smoke test for concat

* Correct docstrings in prelude

* Ensure that type defs are written in module initialization

* Various requested renamings

* Correct rebase snags

* Add kind check tests for ref types

* Update the main() for kind checking tests

* Version 0.5

* update version.py

* update news

* update news

* update news

* move

fix test

fix lint

fix test

add more code

fix lint

better type infer ability

* fix build

* address comment

* update titles to reflect tutorial content (nnvm vs. relay)

* move things around

* fix typo