* layer fixes test=develop

* follow update test=develop

test=develop

* add lod tensor array concat

* add lod tensor array concat

* test=develop

* add lod tensor array concat
test=develop

* Fix API.spec
test=develop

* add lod tensor array concat
test=develop

* revise some bug of lod tensor array concat
test=develop

* add unittest for tensor array concat
test=develop

* change to tensor array to tensor
test=develop

* revise bug
test=develop

* revise a bug
test=develop

* revise a bug
test=develop

* revise a bug of python3
test=develop

avoid the default one that usually overwrites manually set ones

test=develop

This can cause a lot of problem:
1. Wrong operator implementation, Op can get a wrong type without failure.
2. Anytype can be Get without defined in VarType.

Also fix wrong STEP_SCOPE usage.

test=develop

test=develop

* "avoid copy back to cpu"

* "add infinity support"

* "fix ci"

* "add cpu macro"

* rerun ci; test=develop

* "fix api"
test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

This reverts commit 4d8e8ee2, reversing
changes made to d6a9f005.

Give assign layer's second parameter 'output' a default value: None. If
it is None, the output variable will be created inside the layer.

* Update some doc about layers' API.

* Fix format.

* Fix example bug in random_data_generator.

* Fix example bug in dropout.

* Follow comments and some small fix for some examples.

* row_conv
* uniform_random
* layer_norm
* create_parameter
* hard_shrink
* ssd_loss