* Refine mechanism of calling outer function test=develop

* fix typo test=develop

* add dist op

add addmm op

C++ OP enhancement.

* add tdm sampler op

* fix compile bug

* fix compile bug

* fix compile bug

* fix compile bug

* test=develop, add tdm sampler unittest

* fix tdm sampler unittest

* fix input var name bug

* update tdm sampler unittest

* fix unittest

* fix unittest

* update tdm sampler unittest

* add tdm exe run unittest

* fix infershape

* test=develop, add doc

* test=develop, fix gcc8 compile bug & unittest bug

* test=develop, fix unittest

* test=develop, fix T one & zero

* test=develop, add unittest check

* test=develop, add doc smaple code & fix dype set

* test=develop, fix dtype

* test=develop, fix compile bug

* test=develop, fix unittest

* test=develop, fix unittest

* test=develop, check py3 unittest

* test=develop,fix unittest

* test=develop, fix py3&py2 unittest diff

* test=develop, fix sample code

* test=develop, fix sample code

* test=develop, fix sample code

* test=develop, fix error message

test=develop

* refine example code in en doc, test=develop, test=document_fix

* update shape to make it meaningful, test=develop, test=document_fix

* add instance_norm op for dygraph, test=develop

* add error message, test=develop

* add LayerList insert and extend
test=develop

* add index range check
test=develop

* add sample codes
test=develop

* refine sample code
test=develop

* fix init_gflags with 'python -c', test=develop

* enhance error msg related Tracer, test=develop

* refine err msg, test=develop

* follow comments, test=develop

* API(to_variable/save_dygraph) error message enhancement

error message enhancement for fusion_seqpool_concat_op

error message enhancement for py_func op. 

* Involves AfsAPI to resolve slow downloading.
* Mainly used in PaddleBox

* error message enhancement for Conv2DTranspose, test=develop

* fix error_message, test=develop

* solve the conflict of ops with the same name. test=develop

* error message of NCE API enhancement

Fix the bug of matmul test_case