* build gpu task core

* format

* Fix the bug in fleet amp_init.

* Fix the amp_init unit test.

* update document of paddle.vision.dataset, test=document

* update document of paddle.vision.dataset, test=document

* Fix the error of save_quantized_model

* support reduce_max op on kunlun

* support reduce_max op on kunlun

* support reduce_max op on kunlun

* support reduce_max op on kunlun

* optimize unity build, test=develop

* fix code style error, test=develop

* fix code style error and test /MP settings, test=develop

* delay the 'timeout' of 'test_static_save_load'.

* delay the 'timeout' of 'test_static_save_load'.

* delete empty line of pybing.cc, test=develop

* use nvtx push pop in timeline, test=develop

* change year, test=develop

* add #ifdef PADDLE_WITH_CUDA, test=develop

* add #ifndef WIN32, test=develop

* is_pushed to is_pushed_, test=develop

* rewrite abs op

* rewrite abs op and remove abs in activation

* remove abs register in old codes

* fix abs_grad type error

* fix abs double_grad output name error

* modify abs_grad, abs_grad_grad functor for windows building

* format code style

* fix the bug of result is nan when the divisor is zero

* add missing abs attr and add abs for float16

* add fleet amp.init()

* add unittest for fleet_amp_init

* delete empty line of pybing.cc, test=develop

* fix layers train eval bug, test=develop

* update, test=develop

* add paddle.

* add unittest

* add trainers for pserver

Change-Id: I1a75793ec81ce126d07f4c47cae09b95d530bbc8

* add some RecordEvent, for dygraph timeline, test=develop

* change GpuMemcpySync to memory::Copy, test=develop

* fix compile problem, test=develop

* fix compile problem, test=develop

* fix, test=develop

* fix, test=develop

* check UT Duplicate name

* fix error

* Optimized log display

* modified exit code

* add rmsprop_op_xpu test=kunlun

* modified rmsprop_op_xpu error code. test=kunlun

* unify calling cudaSetDevice

* fix compile

* support layer_norm fp16 in dygraph amp

* add ut

* refine code

* add 2.0 API: device_guard