* First pr of paddle slim.
1. Add framework of paddle slim
2. Add filter pruning strategy
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* Rename unitest to tests.
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* Add prettytable into requirements.
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* Change in_nodes and out_nodes to odered dict.
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* Remove distillation.
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* Fix API.spec
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* Fix unitest.
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* Fix unitest in windows.
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* Fix unitest in windows.
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* Fix unitest.
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* Hide some functions.
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* Fix python import in python3.5
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* Fix compress pass.
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* Fix unitest of test_dist_ctr.
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* Enhence flops.

* use os.path.join

* Fix pickle for python3
Fix log and comments.
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* 1. Remove feed_reader in compress pass
2. Fix cache reader
3. Rename CompressPass to Compressor
4. Add comments for distiller optimizer
5. Remove unused pruner currently
6. Add some comments.
7. Change API.spec
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* Fix pruning in python3.
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* Fix unitest in python3.
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* Fix format in python3.
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* Add range op.
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* Add more unitests.
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* Fix API.spec
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* Fix API.spec
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* Fix API.spec
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* Enable INT8 Concat Kernel to improve the performance of MobileNet-SSD.
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* Optimize UT format.
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* Fix UT file address issue.
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* Refine the license year.
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* Optimize code for new API.
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* Restructure INT8 Concat kernel.
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* refine fused_all_reduce_op

* add unit test in test_parallel_executor_seresnext
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* Rewrite gradient ProtoMaker for affine_channel_op to remove the Output as the input.
* Add act in Python API to make the act can be in-place by layer_help.py

* add resnet nccl2 test=develop

* test dist train test=develop

* update test=develop

* increase timeout test=develop

* test on CI env test=develop

* save infer model bug fix, return target vars' name list

* Add softmax_with_cross_entropy_op test=develop

* simplify implementation test=develop

* fuse all_reduce
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* add fuse_parameter_groups_size
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* Polish code
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* Fix travis-ci
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* Add SetGroupAccordingToLayers and SetGroupAccordingToGroupSize
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* Add SetGroupAccordingToMemorySize
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* fix multi_devices_graph
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* reset params_grads
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* Polish code
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* wip allreduce in op

* wip

* wip

* wip

* wip adding test

* wip for conflict with mp mode

* fix tests test=develop

* fix cpu build test=develop

* fix travis clang format test=develop

* fix cpu build test=develop

* update api.spec test=develop

* delete comment test=develop

* fix cpplint test=develop

* fix test=develop

* follow comment test=develop

* add file test=develop

* fix build test=develop

* update test=develop

* to be compatible with sync_bn, and fix mp mode in develop test=develop

* Make step_input support custom lod level.
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* Fix API.spec
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* Fix API.spec.
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* Fix API.spec
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* Add default value in document of step_input.
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* Fix document.
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* Fix API.spec
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* Enable INT8 transpose kernel for MobileNet-SSD improvement.
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* Refine the license year.
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* Delete redundant code.
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* Add axis check.
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* update load persistables for increment, test=develop

* update load persistables for increment, test=develop

* update API Spec, test=develop

* update API Spec, test=develop

* add doc, test=develop

* add doc, test=develop

* Update lookup_table_utils.py

* Update API.spec

* Update lookup_table_utils.py

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* Update API.spec

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* fix api spec

* Update lookup_table_utils.py

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* Add moving average absmax op in quantilize-aware training.

* Support Sync Batch Norm.
* Note, do not enable it in one device.

Usage:

build_strategy = fluid.BuildStrategy()
build_strategy.sync_batch_norm = True
binary = fluid.compiler.CompiledProgram(tp).with_data_parallel(
        loss_name=loss_mean.name,
        build_strategy=build_strategy)

* Impl fp16 compute kernel for slice_op

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* Use data() to replace mutable_data()

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