Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle into add_tensorrt_pooling_converter

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construct a SSAGraph at the beginning.

refine cpu im2col no padding

fix mixed tensor compile and add cpu unit test

Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle into add_tensorrt_pooling_converter

* update test_pe_mnist threshold

* clean code

fix _create_prefetch_block in distribute_transpiler

Remove buggy get_test_program and refine reader demo

Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle into add_tensorrt_pooling_converter

Add rpc complete interface

* Hiden some LoDTensor ralatted ops' Python wrapper.

Enhance for tensorrt infer

* hide variable API

* edit API.spec

Fix learning rate scheduler performance issue

Feature/polish reshape and lod tensor blocking queue

* Add new_doc to develop branch

* Add pics of Anakin tutorial

* Update anakin_tutorial.md

* Delete anakin_fm_en.png

* Delete contri1.JPG

* Delete contri2.JPG

* Update build_and_install_lib_cn.rst

* Update compile_paddle_lib_cn.md

* Update compile_paddle_lib_en.md

* Update install_doc.rst

* Update install_doc.rst