* init commit of new save/load

* fix failed unittests

* fix save_load_v2 unittest failed

* fix failed unittest & polish doc

* add tests for coverage

* add more tests & move static apis

* fix example code error

* polish emample code

* fix detail example code problem

* Makes the Bind Method more intelligent

* Makes the Bind Method more intelligent

* fix unittest

* fix unittest

* fix conflict

* remove paddle.readers API. test=develop

and optimize the c++ implmentation of empty op as PR#26659 reviews,
and add bool for shape op.

* bug fix, test=develop

* temporally disable zero_copy

* add test

* follow comments

* fix frobenius_norm error, rm p=0 2-axis support. test=develop

* fix unsqueeze in dygraph

* add test

* add test

fix the bug for dtype check for the argmin/argmax

update the check for the dtype check for the argmin, argmax

update doc of paddle.to_tensor

* fix unittest format and extract common function

* change function name

* set_default_type only take effect on python floats or complex

* fix doc

* refine paddle.stack

* support TensorArray

* add test

* fix coverage problem

* fix coverage problem

* fix sample code

* fix the argmin,argmax op for the paddlepaddle 2.0， add checkPoint for the argmax/argmin

* add check for bernoulli and register bool for unsqueeze

* follow comments

* set default dtype for distribution API

* Add unittest

* Add unittest

* fix import get_default_dtype problem

* delete change under fluid.layers.nn

* little change

* add set_default_type for tensor

* fix doc

* fix doc

add parameters check in static mode for diag op 

* Fix clip input check

* Fix default min/max value

* Allow both max and min to be None

* Register op change

* Revert OP signature change

As the title

* update doc, test=document_fix

* add attr(dtype)

* refine code

* fix the tanh

* fix the learning rate

add the top v2 for the paddlepaddle api 2.0