* add deprecated memory optimize doc, test=develop, test=document_fix

* merge develop to solve conflict, test=develop, test=document_fix

* deprecate python memory optimize, test=develop

* remove memory_optimize in unittests, test=develop

* add unittests to deprecated interfaces, test=develop

* remove legacy memory optimization codes, test=develop

* follow huihuang's comments,test=develop

* follow luotao's comments, test=develop

* fix default value of fluid.memory_optimize
test=develop

* fix api.spec
test=develop

* fix doc in transpiler, test=develop

* improve the doc of paddle.fluid.memory_optimize, test=develop

* fix typo, test=develop

* improve the API Sample of DataFeeder, memory_optimize and release_memory, test=develop

* update API.spec, test=develop, test=document_preview

* tweak the code format of feed API, test=develop

*  update API.spec, test=develop

* improve doc for DataFeeder and default_main_program, test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

* follow comments. test=develop

* Fix typo

* fix compile error. test=develop

* merge develop branch. test=develop

* Remove set_equal

* Polish code

* Delete unused functions

test=develop

* polish code. test=develop

* follow comment

* polish code.

* fix windows compile error. test=develop

* fix op handle.

* rerun ci. test=develop

* rerun ci. test=develop

* rerun macci. test=develop

* polish code. test=develop

* rewrite sort code. test=develop

* remove unused code. test=develop

* fix tests. test=develop

* fix conflict. test=develop

* follow comment. test=develop

* merge develop branch. test=develop

* fix tests. test=develop

* remove ToTypeIndex. test=develop

* rerun ci. test=develop

* test=develop

* fix tests. test=develop

test=develop

* random failed. rerun ci. test=develop

* windows failed. rerun ci. test=develop

* show detail error log on ci

* test

* fix memopt and dist

* update apispec

* will fix different batch issue test=develop

* wip

* clean up

* should fix running with memopt

* add ut

* mark lr schedule op role

* hide lr_schedule_guard

* use op_role_var instead of ufind

* unify dist test name

* wip for py3 support

* fix var deref

* fix python3 mem_opt order

* remove comments

* hide program APIs

* fix merge error

* update

Fix pb_protobuf2 FromString problem