* yolo_box OP add Attr(clip_bbox). test=develop

- ngarph: elementwise_sub, elementwise_mul
- mkldnn: transpose, sum
- others: scatter_nd

test=develop

test=develop

test=develop

* fix elementwise_pow bug on integer, test=develop

* use llrint to support elementwise_pow_grad, test=develop

* add some tests, test=develop

* revert grad functor, test=develop

* patch math method for varbase using auto-generated op functions, test=develop

* clean code that handles batch_size, test=develop

* follow comments, test=develop

* follow comments, test=develop

* code clean, test=develop

* fix compile error when WITH_PSLIB=ON
* test=develop

* add backward unittest test=develop

* add sub-branch in test_backward.py test=develop

* refine code, add comment test=develop

* reconstruct TestBackward Class test=develop

* fix typo of comment test=develop

* fc-dequantize squash
test=develop

* change according to reviews
test=develop

* change PADDLE_ENFORCE
test=develop

* add second test when fc-dequant do not fuse
test=develop

* change all related PADDLE_ENFORCE
test=develop

* rename paddle throw error macro, test=develop

* fix new error use case, test=develop

* update op test framework

affine_grid, label_smooth, spectral_norm, warpctc,
nearest_interp, data_norm, match_matrix_tensor,
var_conv_2d, fused_embedding_seq_pool

test=develop

sequence_expand_as, squared_l2_distance, gather_nd,
center_loss, rank_loss, conv_shift, spp,
modified_huber_loss, smooth_l1_loss, multiplex,
sequence_softmax, nce, huber_loss, group_norm,
kldiv_loss, hinge_loss, expand_as

test=develop

* polish cmake, test=develop

* add current directory to LD_LIBRARY_PATH, test=develop

* Add reshape int8 op

test=develop

* Change test to CPUPlace

test=develop

* Correct tests

test=develop

* fix test for PY3 test=develop

* reduce file changes test=develop

sequence_unpad, expand, pad, pad_constant_like,
norm, bilinear_tensor_product, flatten2, im2sequence,
unpool, cos_sim, strided_slice, flatten, elementwise_min,
abs, acos

test=develop

* ci_check
test=develop
test=document_fix

* test error
test=develop
test=document_fix

* check another op accuracy ci
test=develop
test=document_fix

* converge to one if
test=develop
test=document_fix

* remove test case
test=develop
test=document_fix

* simplify ci check
test=develop
test=document_fix

* remove test case
test=develop
test=document_fix

* optimize ci check
test=develop
test=document_fix

* optimize ci check
test=develop
test=document_fix

* remove test case
test=develop
test=document_fix

* add fake init for the trainer, fix large memory hold in the trainer
* do not merge recv vars from a remote endpoint, test=develop
* add recv and save op, merge slice var in one op, save memory
* remove hsigmoid with pull sparse, test=develop

* fix input shape of op tests for elementwise_sub,
gather, pad2d, transpose, softmax, scale,
elementwise_max, hierarchical_sigmoid, reshape2,
sign, squeeze, reduce_sum, sum, squeeze2,
unsqueeze, unsqueeze2, cast, reverse

test=develop

* fix cast, elementwise_mul, gather, scale, sign,
softmax, transpose

test=develop

* change several tests to use the right parent class, test=develop

* add dtype for TestLoDTensorAndSelectedRowsOp, test=develop

test=develop