Merge pull request !830 from Jamie/operator_print

2. add relative path support in resnet50 example
3. optimize allreuce split strategy

Merge pull request !856 from jiangzhiwen/dataset/skip_thread

fix DiagPart constant folding issue

fix argmin output type check

fix atan2 doc error

fix remove FusedBatchNorm and its grad

Merge pull request !835 from lihongkang/master

Merge pull request !858 from xiefangqi/md_fix_gpu_issue

Merge pull request !844 from chujinjin/add_accuracy_for_resnet_cifar

Merge pull request !829 from ghzl/parser-parameter-in-tuple-in-run_op

update mindspore/ops/operations/other_ops.py.

Merge pull request !852 from lianliguang/master

Merge pull request !839 from wangnan39/add_parameter_verification_for_rmsprop

Merge pull request !833 from wandongdong/master

Merge pull request !841 from zhangbuxue/adapt_ExtractImagePatches_and_fix_EluGrad

Merge pull request !823 from huanghui/BatchNormGrad-split-pass

Merge pull request !845 from fary86/add_error_type_index_error

Merge pull request !848 from yanghaitao/yht_generator_sampler_numshards

Merge pull request !84 from zhaozhenlong/adapt-apply-adam-d

Merge pull request !721 from candanzg/tensor_assgin_ellipsis

Merge pull request !727 from Chong/cost

Merge pull request !846 from 梅晓蔚/master

Merge pull request !814 from xychow/compare-with-context-ptr

Merge pull request !802 from chenfei_mindspore/move-opt-into-build-graph

Merge pull request !81 from yanzhenxiang2020/fix_isfinite_input_check

1. Remove the records of user graphs;
2. Remove the records of user value nodes;
3. Remove the records of user cnodes;
4. Add the records of users, and the API to access the users of graph, value node, and cnode;
5. Fix issue:User cnode record may point to its own graph, when combine the user(caller) and used one(callee);
6. Fix issue:User graphs never update itself after its first creation.

Merge pull request !75 from changzherui/syn-code428