Add group normalization operator.

* Fix truncated normal.

* Fix.

* Make nce support more distribution.

* Fix API.spec.

* Fix python API.

* Fix.
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* Fix API.spec
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* Fix sampler.

* Fix order of arguments in python API.
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* add cudnn ctc loss

* wip add test test=develop

* wip

* wip

* done test=develop

* move include cudnn test=develop

* test test=develop

* fix build test=develop

* fix build test=develop

* fix build on cudnn5 test=develop

* fix cudnn5 build test=develop

* fix cudnn5 build test=develop

* merge develop softmax functor change test=develop

* add selu

* use for range
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* add API
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* follow comment
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* update API.spec
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* Support softmax return in softmax_with_cross_entropy

* Add test for return_softmax=False

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Density prior box operator for image detection model.

* add lod tensor array concat

* add lod tensor array concat

* test=develop

* add lod tensor array concat
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* Fix API.spec
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* add lod tensor array concat
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* revise some bug of lod tensor array concat
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* add unittest for tensor array concat
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* change to tensor array to tensor
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* revise bug
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* revise a bug
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* revise a bug
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* revise a bug of python3
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* Add affine grid generator.

* fix ffine grid.

* Add unitest.

* Add CPU kernel and fix unitest.

* Fix CPU kernel.

* Refine code.
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* Fix python api.
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* Update python api.
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* Fix comment.
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* Rename affine_grid_generator to affine_grid and enhence unitest.
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* Fix unitest.
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- Added rough profiling

- Profiled maxpool itself

- First draft of max seqpool optimization (is_test added)

- Added unit tests to seqpool

- Cosmetic fixes

- Fix to UT of Seq pool

Disabled grad checking for sequence max pool when is_test is set to True

-Cosmetic fix to comment

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- Fix to GPU build

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- yet another GPU fix for sequence max pool

- Fix to comment

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- Change to API of sequence_pool

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- Yet another API spec change

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* fix nccl2 lars dist support

* put lars in momentum op

* add tests lars

* fix ci

* fix cpu kernel

* soft warning

* remove lars in test_recognize_digits.py

* move to another op

* add file

* update api.spec test=develop

* update test=develop

* fix api.spec test=develop

* wip

* wip, finish grad merge ops

* wip, finish graph build

* wip test running

* work on 1 gpu

* workable version

* update

* fix tests

* fuse broadcast op

* fix compile failed

* refine

* add batch merge test mnist

* fix CI test=develop

* fix build

* use independent bn params for batch merge test=develop

* update api.spec

* follow comments and for test

* wip

* refine tests test=develop

* follow comments test=develop

* remove startup bn modify test=develop

* follow comments test=develop

* fix merge test=develop

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* fix conv doc
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* fix seq_conv doc
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* fix simple_img_conv_pool
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* update API.spec

* update parameter doc
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* follow comment
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* fix other layer
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* fix lstm bias_attr doc
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* Add affine channel op.
* Update code and add Python API.
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* Update API.spec
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