* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* add recompute for pp

* add recompute offload

* add recompute partition

* add save/load for pipelineparallel

* add save/load

* fix bug of p2p for partial

* fix error

* add layer segment

* add segement for transformer

* add utest

* support 1f1b for pipeline

* add utest

* add send_partial/recv_partial

* support amp for pp

* fix logger