* Modify lod_tensor.md and nn.py

* Modify control_flow.py doc

* undo change in lod_tensor.md

remove mkldnn flag from gtest strdup for cpu

* add lod_tensor util and modify pybind

* refind pybind LoDTensor API and modify LoDTensor and DataFeeder test

* fix test error

* fix detection map op test

* fix reorder_lod_tensor test

* fix seq_concat_op

* fix chunk evel op test

* fix target assign op

* fix warp ctc op

* address comments step 1: reverse reset_lod op

* step 2: modify op test

* add warning message

* remove has_valid_lod

* add back has_valid_lod

* address comments

* add exception catching trial

Fix some problems in api reference

Add doc for while and piecewise_decay op

add doc of sequence_softmax and parallelDo

Refine test and scope lock

* Implement a bilinear initializer for transposed convolution.

* Update some error message.

* Update some doc about layers' API.

* Fix format.

* Fix example bug in random_data_generator.

* Fix example bug in dropout.

* Follow comments and some small fix for some examples.

skip all tests in tests_parallel_executor_crf

Fix dist ut

Polish inline math and duplicable/optional in auto generated doc

Doc update