* Merged LoDTensor with Tensor,test=allcases

* Patched python level LoDTensor

* Fixed example code failure

* Polished function names, removed duplicated forward declarations

* use iwyu clean include, test=develop, test=win

* compilation error, test=develop

* fix compilation error2, test=develop

* fix compilation error3, test=develop

* fix compilation error4, test=develop

* fix compilation error5, test=develop

* fix compilation error6, test=develop

* fix compilation error7, test=develop

* fix compilation error8, test=develop

* fix compilation error8, test=develop

* fix compilation error10, test=develop

* fix compilation error11, test=develop

* refine error msg in var_handle.h, test=develop

* refine all_reduce_op_handle

* fix some error msg

* refine variable_visitor

* refine threaded_ssa_graph_executor

* refine inplace related files

* refine executor related files

* refine fetch_op_handle.cc

* fix bug

* follow comments

test=develop