* add paddle.neg api

* add test for neg

* fix an English gammar error in comment

* add lgamma api

* support api paddle.tensor.neg() and paddle.tensor.lgamma()

* modify test_neg_op.py

* update, test=develop

* Support append customize attributes into op_desc in nn.Layer

* fix code style

* support override

* add unittest

* add random state generate in DataLoader worker. test=develop

* add parallel_cross_entropy

* add grad for crossentropy

* fix cross entropy

* support state_dict save to memory.

* Perfect unittest

* perfect unittest.

* suport saving binary var to memory

* polish code.

* packag save/load files into pybind/io.py

* polish code .

* add example for save to memory; remove useless save load function(_load_static_dict,_save_dygraph_dict)

* delete _load_static/dygraph_dict;_save_static/dygraph_dict

* edit example of paddle.save/load

* modify API nn.Bilinear's doc, test=develop

* add two attributes for yolo box

* Add wrap for functional api
* Refine the wraped api
* Add unit test for quant functional layers
* Update all unit tests for dygraph qat

* replace 'InnerSetOverridedStopGradient' with 'SetOverridedStopGradient'.

* improve coverage.

* polish error message.

* add dynamic layer_norm plugin

* fix bug

* fix numpy.allclose

* fix format

* fix code style

* remove shepe in dynamic shape

* code format

* remove layer norm fp16

* fix format

* Fix two english api documents, transpose and strided_slice

* OP:strided_slice_op supports bool type inputs

* add private api for memcpy_op

* change place dtype

* add private python api for memcpy op

* fix c_split bug

* fix utest

* add c_embedding for tensorparallel

* fix inference prepare data bug

* rename functions

* typo

* typo

* typo

* UT correct

* correct condition

* correct condition

* ci coverage

* morelines

* fix ci coverage

* fix stop_gradient in paddle.to_tensor

* make to_tensor copy if data is varbase

* add ut

* refine sample code

This PR made these changes to support double grad:

1. Translate `paddle.grad` to `paddle.static.gradients` to support double grad for dy2stat.
2. Fix IfElseTransformer bug which may not change value if "Store before Load" variable is in "Store" statement is in IfElse conditional statement
3. Add `DOut` to support double grad variables in `run_program_op`
4. Add support for renaming for double grads for `jit.save/load`

* Dygraph Recompute support AMP

* dygraph recompute: update unitest

* fix the bug of div operation result using scale method do not exactly equal the result of elementwise_div method

* remove __div__ , __rdiv__ methods which do not define in python3

* modify the note

* add test case

* add test case

* add trt convert op: reshape

* reshape

* fix

* input: Shape,ShapeTensor

* Add some comments

* fix spawn default nprocs get error

* polish error message

* fix syncbn