test=release/1.4

* fix the bug of reusing different types of variables in memory_optimiz… (#16547)

* fix the bug of reusing different types of variables in memory_optimize_pass, test=develop

* disable SELECTED_ROWS AND LOD_TENSOR_ARRAY reusage, test=develop

* only use the latest version variable for inplace strategy (#16736)

* bug-fix, test=develop

* tweak code, test=develop

* cherry-pick PR 16547,16736,16739 test=release/1.4

* fix comments of 16410, test=develop

* modify inplace_op_inference_test according to pass interface change, test=develop

* modify the interface of Pass::Allay
test=develop

* Polish code
test=develop

* Fix Travis CI
test=develop

* fix Pass::Apply interface
test=develop

* Fix Travis CI
test=develop

* fix cdn issue, test=develop

* fix memory optimize bugs, test=develop

* fix memory optimize bugs, test=develop

* remove add/sub_2 op, test=develop

* disable memory_optimize by default, test=develop

* disable inplace activation in python, test=develop

* fix unittests, test=develop

* fix unittests, test=develop

* bug-fix, test=develop