* Support int8 type.

This reverts commit b2df1700.

* dist transpiler add control dependency var between send and recv

* fix async deps

* follow comments and refine

* fix deps connect for rpc ops

* Add Python Callstacks when Op::Run error

* Skip op with sub-block

* refactor: refine callstack info's format

* Reshape only support matrix

* Polish Python code

* Fix UT

* Fix Py3

Optimize selected rows for dist lookup table with rwlock 

* hide misc APIs

* update

* fix transformer test

* update API.spec

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

* remove block api

* remove clone_variable

* hide block inner apis

* update

* fix tests

* move to platform

* "move init from framework to platform"

* "remove used init"

* "fix ci"

* "fix ci"

* "fix generic"

* "fix ci"

* "fix ci"

* "fix ci"

* "disable fragile test"