update split_lod_tensor, create_array and array_length doc

Fix api reference docs

Hide StaticRNNMemory

 Fix doc of warpctc, array_read, edit_distance and sequence_reshape.

[API Reference] fix some typo in layers

Fix doc of relu, log and zeros.

Add API reference

Fix conv3d/conv3d_trans/slice/mean_iou Doc

* 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