* Create and register ONNX Dialect with one Add operation.
* Fix file formatting.
* Change name from ONNX to SGIR.
* Use ONNX dialect. Change SGIR to frontend placeholder dialect.
* Add comments.
* Type clean-up.
* use table gen
* fix name of the dialect
* add old compilation path
* add some doc
* fix bug, sgir importer imports every op twice
* knl.visit -> knl.iterate