* First pass at Relay-to-Python converter testing utility
* Indicate astor as a dependency
* Add astor dep to host as well
* Typos and small bugs
* Handle ADTs and matching in Python conversion
* Remove any dependency on ast.parse
* Eliminate unnecessary type var field in Python version of ConstructorValue (already gone on C++ side)
* Update constructor value, fix syntax errors
* Don't forget keywords arg on Call nodes
* Fix some incorrect calls to ast nodes
* Fix more calls, a little more cleaning up
* Missing cases in attr conversion
* Lower op calls instead of running them through interpreter, as in @MarisaKirisame's AoT compiler
* We do still need the module
* Remove changes to op attrs: Will PR separately
* Smoke test and corrections
* More tests and fixes
* Ensure imports are properly global in generated Python code
* Add unit tests for refs
* Add unit test for tuple indexing
* Add unit test for if expression
* Remove astor dependency
* Remove astor from meta.yaml too
* Fix if test and add basic local function test
* Add global function test, refactor earlier tests
* Correct 'clause' field in ADT so Python and C++ field names match
* More fixes and tests for matching and constructors
* Dramatically simplify matching: no need for a thunk
* Improve ref writing test
* Ensure local recursion works
* cleanup
* Add test for global recursion
* Add test for higher-order calls
* Get ops working, add basic tests
* Remove accidentally duplicated test
* More docstrings to appease pylint
* Forgot to fix a test using constructor values
* Reduce optimization level in fusion and fix tuple input to operators
* Test op with tuple output, fix tuple output code
* Add unit test for batch norm
* Add a couple more tricky test cases
* Correct nat constructor to drop unnecessary field
* Fix the op attrs file (accidentally reduced it)
* Address review comments
* Adapt to new ConstructorValue representation (no more runtime dep on module)
* Use pass manager and updated interfaces. Extend module.from_expr to accommodate necessary demands
* Use sequential return value
* Lift out nested conditionals
* Replace triple single quotes with triple double quotes
* Use main variable instead of entry_func
