Add float16 support to relu op

fluid distribute doc

Softmax MKLDNN FLUID operator

removed diagnostic

- Added Unit tests for Softmax MKLDNN Forward

Added fix for div by 0 to happen in cross_entropy backward

Conflicts:
	paddle/fluid/operators/CMakeLists.txt

- Cosmetic fixes to SoftMax MKLDNN fluid operator

Added misssing softmax fluid operator file

Disabled MKLDNN softmax operator by default

Fix to softmax op unittest merge

clang_formater fixes

clang_formatter fixes

- Name changing of softmax mkldnn operator to maintin consistency
  across codebase

- updated comment

fix to comment

Update index_en.rst

Add float16 support to batch norm operator

Multi-pass reader

repair image link in rnn.md

Add an argument in Executor.Run to allow users to choose whether to create and destroy variables every time. (#9242)

Multi-threaded reader in C++

Fix a bug of RecordIO

change the path of image code

* Create select_op design document

* Fix pre-commit issues

* Update select op as per varun's comments

expose dilation to conv2d and bias/act to con2d_trans

Add float16 support to Elementwise Add op

Update index_en.rst