* add export model for ofa (#548)

* OFA demo for ernie (#493)

* cherry pick

* fix bug when paddle upgrade (#606)

* add jpg

* fix when param name is not None

* fix nas (#553)

* fix when lambda_distill is None in ofa (#550)

* fix

* fix when lambda is None

* fix when the task is mnli (#540)

* fix

* fix when mnli

* Fix ofa (#536)

* fix

* fix embedding
Co-authored-by: NBai Yifan <me@ethanbai.com>
Co-authored-by: NBai Yifan <me@ethanbai.com>

* fix

* fix embedding
Co-authored-by: NBai Yifan <me@ethanbai.com>

* for bert

* support 2.0

* fix bugs for ernie

* add ofa

* Fix import in py3.

* Update bert distillation.

* Add option to fix embedding in bert distillation.

* Fix distillation in adabert searching

* Remove unused code

* fix

* refine warning

* add darts unittest

* refine reader config

* support multi-cards in darts

* fix

* fix win

* add darts en api doc

* add darts ch api doc

* fix example code

* fix

* fix some trouble

* update

* fix sa api docs

* update

* update

* update

* add darts

* update fix

* fix init token

* fix bug

* update

* update doc

* update

* update readme

* update

* update