replace paddle.fluid.layers.selu with paddle.nn.functional.selu

* Remove API: gather
	replace the paddle.fluid.layers.gather with paddle.gather

* modify the call of gather from old style to new style

* remove range

remove pad_constant_like which is not used in paddle 2.0

* remove unstack in nn.py under fluid

* remove unstack under fluid

* clean fluid elementwise_pow, remove API

* clean elem_pow doc

* clean elementwise_mod

* clean elementwise min, floordiv, mod

* remove swish in nn.py under fluid

* fix tswish test case

* clean fluid elementwise_min

* fix elementwise_min op testcase

* remove chunk_eval

* [Zero-Dim] support input 0D Tensor as scalar attribute for some api

* fix doc

* standard api

* fix sparse bugs

* fix xpu bugs, test=kunlun

* remove hard code for custom unittest

* open ci, test=kunlun

* deal with conflict

* [Zero-Dim] support input 0D Tensor for sundary api

* fix comment

* [CodeStyle][py2][U004] unecessary explicit `object` inheritance in class definition

* fix an increment

* move fluid.layers.deformable_conv to static.nn

* modify example code

* fix doc

* Update common.py
Co-authored-by: NLigoml <39876205+Ligoml@users.noreply.github.com>

* [CodeStyle][py2][U008] remove unnecessary args in `super()`

* remove remained args

* revert changes in test_pylayer_op

* Revert "revert changes in test_pylayer_op"

This reverts commit ff185a9ae738afac3b0264f61bde6c6b7f72e7c4.

* revert some changes in example code

* [CodeStyle][E711] use `is`/`is not` for comparison with `None`

* `self.assertTrue($A is None)` -> `self.assertIsNone($A)`

* `self.assertTrue($A is not None)` -> `self.assertIsNotNone($A)`

* `self.assertFalse($A is None)` -> `self.assertIsNotNone($A)`

* `self.assertEqual($A, None)` -> `self.assertIsNone($A)`

* `self.assertNotEqual($A, None)` -> `self.assertIsNotNone($A)`

* standard_api

* add hardtanh

* [CodeStyle][py2] remove `six` package (part2)

* six.ensure_str

* remove unused `import six`

* remove six from BUILTIN_LIKELY_MODULES

* remove six in example code

* remove some decode

* try to fix example code

* fix MockEtcdClient get/get_prefix returns data type

* fix MockEtcdClient get_prefix returns data

* fix MockEtcdClient get returns data

* remove `six` in pypi and conda requirements

* fix MockEtcdClient add_watch_callback/add_watch_prefix_callback returns data type

* refine MockEtcdClient

* standard api

* fix ci bugs

* fix ci bugs

* fix ce bugs

* fix typo `Fasle`/`Flase` -> `Flase`

* fix typo `Ture` -> `True`

* [CodeStyle][py2] remove `paddle.compat`

* remove compat from `paddle.__init__`

* enable_static in sample code

* Revert "enable_static in sample code"

This reverts commit ffccaa633900154ea5f3d056e746aae9a1927399.

* enable_static in sample code

* fix bugs while cond receives dict as input

* add unittest

* change flatten -> _is_sequence_except_dict

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* rename op in yaml

* fix test_layout_autotune

* fix layout autotune of transpose

* [CodeStyle][py2] remove `compat` module (to_text)

* remove some unnecessary decode

* remove to_text definition and unittest

* Revert "remove to_text definition and unittest"

This reverts commit a6b69cb8dca8b9b031ce10ea32d1040e7e0dd267.

* remove an assertion

* empty commit

* [CodeStyle][py2] remove `compat` module (to_bytes)

* remove some unused imports

* clean up to_bytes definition and unittests

* Revert "clean up to_bytes definition and unittests"

This reverts commit e726539e1768172a411ff60e63fab82f164343cf.

* use `b` prefix instead of `encode()`