* update linspace, equal operators to API 2.0, test=develop

* equal support higher performance CUDA kernel, test=develop

* update comment of equal&linspace operator, test=develop

* update comment of equal&linspace operator, test=develop

* improve elementwise performance.

* Add contiguous check, test=develop

* prune train program by fetch_list, test=develop

* add unittest for prune, test=develop

* fix pruned feed, test=develop

* support ParallelExecutor and feed prune, test=develop

* add comments, test=develop

* update unittest, test=develop

* update unittests, test=develop

* remove debug code, test=develop

* support cond in clone, test=develop

* support cond in prune, test=develop

* support multiple minimize, test=develop

* support cache, test=develop

* fix _copy_param_info_from, test=develop

* support python2 str, test=develop

* remove debug code, test=develop

* fix bug of caching CompiledProgram, test=develop

* fix multi_device issue, test=develop

* tmp

* support tuple in fetch_list and overriding use_prune, test=develop

* dont use nonlocal in python2, test=develop

* remove nonlocal, test=develop

* code clean, test=develop

* code clean, test=develop

* feed list, test=develop

* test adam, test=develop

* follow comments, test=develop

* reduce duplicate code, test=develop

* update comments, test=develop

* add op inout check macro, test=develop

* fix enforce_test, test=develop

This reverts commit 48144e40.

* Add unittest for transformer prediction in dygraph_to_static.

* fix bug in fill_constant api. 

* Make transpose support size 0. test=develop

* fix stat var in hogwild worker
* test=develop

* use global conv cache; test=develop

* use singleton cache; test=develop

* fix format error; test=develop

* add cudnn helper header; test=develop

* fix header error; test=develop

* fix mac unitest; test=develop

* fix mac unitest; test=develop

* fix file format; test=develop

* fix include file error, test=develop

* remove kernel_configs_ in class ExecutionContext and kernel_configs_map_ in class OperatorWithKernel, test=develop

* fix test_elementwise_mul_op_dim, test=develop
Co-authored-by: Nphlrain <phliuhongyu@126.com>

* Delete is_test from activation operators
test=develop

* Revent unneeded changes
test=develop

* add inplace_abn_op. test=develop

test=develop

* refine the error message of tensor_array_read_write Op

* add attr support for fusion group and add support for fill_constant and scale Op

* add fleet pslib pull and push sparse op and push dense op
* test=develop

test=develop

test=develop

As nccl comm is not created by CUDADeviceContext, it should be destroyed by the creator as the best practice of RAII.

* refine output of profiler for child event 

* expand parameters, test=develop

* support resnet, test=develop

* fix resnet, test=develop

* support duplicable out, test=develop

* support ptb

* fix bugs, test=develop

* support null input, test=develop

* fix bugs, test=develop

* fix batchNorm is_test, test=develop

* refine code, test=develop

* follow comments, test=develop

* follow comments, test=develop

* follow comments, test=develop

* follow comments, test=develop

* distinguish public/private vars, test=develop

* fix windows issues, test=develop

* Improve elementwise performance.

Elementwise performace is poor as walk into CommonGradBroadcastCUDA, add some new kernels for different data pattern.

* Add some cuda kernel to speedup common broadcast cases. test=develop

* Add more test cases and fix cuda kernel bug. test=develop

* Remove tests as cpu percision fails.test=develop

* Refine SplitDims, test=develop

* Change file mode, test=develop

* expose dygraph.grad api, test=develop, test=document_fix

* add more parameter in dygraph.grad API, test=develop

* add only_inputs=True parameter, test=develop

* follow comments, test=develop, test=document_fix

* fix typo, test=develop, test=document_fix

* add inference api doc. test=develop

test=develop