* API/OP (margin_rank_loss, nce, row_conv, glu, positive_negative_pair) error message enhancement, test=develop

* add unittest for glu, test=develop

* enhance add_position_encoding error message, test=develop

* enhance warpctc & scaled_dot_product_attention error message, test=develop

* modified error message and ctest of scaled_dot_product_attention, test=develop

* add inplace_abn_op. test=develop

* Fix api docs. test=document-fix

* Fix en docs. test=develop

* Fix the doc of dynamic_gru. test=document_fix

* Update API.spec. test=document_fix

* Fix codestyle test=develop, test=document_fix

* Fix several api docs

test=develop, test=document_fix

* modify document of 11 APIs
test=develop
test=document_fix

* fix dtype to data type and description of name parameter

* update api example, test=develop, test=document_fix

* update en doc

* Fix the example code in some Python API.
test=develop

* Fix the example code in some Python API by adding import.
test=develop

* fix API examples, test=develop

* fix conv doc
test=develop

* fix seq_conv doc
test=develop

* fix simple_img_conv_pool
test=develop

* update API.spec

* update parameter doc
test=develop

* follow comment
test=develop

* fix other layer
test=develop

* fix lstm bias_attr doc
test=develop

Add API.spec

test=develop

This reverts commit f5d5d7b2.

* Disable in_place in batch_norm API.

* MKLDNN pool2d OP kernel added

* conv2d and pool2d MKLDNN kernels renamed

* MKLDNN conv2d kernel refactoring

* MKLDNN conv2 OP kernel added

* TODOs added

* mkldnn conv2d OP refactor

* CanCUDNNBeUsed and CanMKLDNNBeUsed moved