1. Add a new attribute named 'startuo_seed' to RandomCropOp. If the input
'Seed' is not initialized, the 'startup_seed' will be used to replace
it.

2. Refine CustomReader. Add a member variable 'scope_' to it. The
'scope_' will act as the global scope of preprocesing, making it
possiable to save something cross batches.

Give assign layer's second parameter 'output' a default value: None. If
it is None, the output variable will be created inside the layer.

* Add sub_blocks of lr_decay_op to pserver_prog after distribute_transpiler

* Remove unused logs and logics

* 1. Add ops to new block (considering the nested block condition)
2. Follow the original hierarchy of blocks
3. Change the function's name and remove debug lines

refine the initial cpu memory flag for mkldnn

concat support data as input

add doc for inference_transpiler

MKLDNN layout: Support for activation operator

* Remove tape

* remove tape in cmake

* fix CI

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