* Add `device` parameter to ExtraAttr in trainer_config_helpers.
* add unittest for it.

* fix bug in dotmul_operator's api and anotation
* update rnn document
* remove redundant info of projection and operator in layers.py

* split dotmul_projection and dotmul_operator
* bug fix in outputsize checking for mixed layer

Sequences should be sorted according to the number of subsequences they have.

Sequences should be sorted according to the number of subsequences they have.

* Add some comments for CTC layer and fix CTC evalutors, also add interface test

Change cos_sim to use CosSimLayer layer when size=1 and rename convex_comb_layer to linear_comb_layer

Also add an unittest for layers.py, currently for a few things. More need to be added later.

* Fix ParameterAttribute for img_conv_layer, tensor_layer, crf_layer, crf_decoding_layer.

Change-Id: Ic24e4bc1f9d5e03bf35058b49a54c78caf7e97a8

ISSUE=4619881 

git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1502 1ad973e4-5ce8-4261-8a94-b56d1f490c56

ISSUE=4612671

git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1501 1ad973e4-5ce8-4261-8a94-b56d1f490c56

ISSUE=4612433 

git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1476 1ad973e4-5ce8-4261-8a94-b56d1f490c56

ISSUE=4611081


git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1475 1ad973e4-5ce8-4261-8a94-b56d1f490c56

ISSUE=4611579

git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1473 1ad973e4-5ce8-4261-8a94-b56d1f490c56

ISSUE=4599577


git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1440 1ad973e4-5ce8-4261-8a94-b56d1f490c56

ISSUE=4592807 

git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1423 1ad973e4-5ce8-4261-8a94-b56d1f490c56

ISSUE=4539687

git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1422 1ad973e4-5ce8-4261-8a94-b56d1f490c56

Also add some comments for cost layers.
ISSUE=4580653

git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1410 1ad973e4-5ce8-4261-8a94-b56d1f490c56

ISSUE=4586495

git-svn-id: https://svn.baidu.com/idl/trunk/paddle@1408 1ad973e4-5ce8-4261-8a94-b56d1f490c56