Refine the doc of layers.py

Refine roi_pool_op to avoid warning

Add Factorization Machine Layer

* Fix the latex comment syntax in sgd_op.cc

* Change \textunderscore to \_

* Complete shrink_rnn_memory_op comments

* Update

Update the annotations of layers.py.

* Restore the param infos in Program.clone()

The Program.clone only clone the variables and ops
in the program into a new program. However, the
information of Parameter is not clone.

So we need restore the information of Parameters.

Fix #5871

* Follow comments

* Fix CI

* Fix CI

* Fix CI

* py_test support argument, test_image_classification_train support argument

* use REMOVE_ITEM to rm item from list in cmake

Update installation docs

Fix the check in addto_layer

Change books just use `import fluid`, not submodules

* Add documentation of cProfile tools

* Complete doc

* Refine code

Fix bug in RoI pooling.

* conv cudnn 3d

* update test case

* update

* update

* follow comments and remove groups from helper

* update

* refine

* update

* follow comments2

* update

* fix compile

* "add asnumpy interface"

* Just for unittest

* Change unittests for numpy I/O

* Fix CI

* Stash

* Stash

* Polish Evaluator

* Merge code

* Revert