* dist transpiler add control dependency var between send and recv

* fix async deps

* follow comments and refine

* fix deps connect for rpc ops

* add async dist tests

* update delta

* fix transformer test

* refine rmsprop transpile

* update

* fix dist seresnet

Port dist_transpiler new added codes
Port ut for clone desc

Add dependency to send recv

* dist transpile can pass startup program by argument

* update API.spec

* hide misc APIs

* update

* fix transformer test

* update API.spec

* fix dist train with rmsprop

* add rmsprop transpiler test

* update by comment

Fix str and bytes problem
Fix sorted problem
Fix math problem
Fix CI problem

better test

* hide variable API

* edit API.spec

* remove block api

* remove clone_variable

* hide block inner apis

* update

* fix tests