support for 1 specific dimension to be None, added validator

fix various CI complains

another round of CI fixes

ci

refactor parts of the code

code refactor

ci fix

comments added, fix bugs

address review comments

address review comments

review cmts

added simple perf test script

update pad code

perf imprv

Merge pull request !847 from ZhangQinghua/opt

Merge pull request !869 from JesseKLee/random_data_op

Merge pull request !794 from zhaozhenlong/fix-issues-image-gradients-complement-check

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 !657 from huanghui/fix-confusionmulgrad-fusion-pass

Merge pull request !695 from YuJianfeng/master

Merge pull request !430 from Etone.Chan/bufferfusion

This reverts commit ea6958c50a.

Merge pull request !264 from xychow/remove-unnecessary-cache-and-add-cache

Merge pull request !621 from liyong126/mindrecord_ut

Merge pull request !554 from huanghui/fix_derelu_fusion_pass

Merge pull request !492 from YuJianfeng/allgather

Merge pull request !556 from Chong/partition

add cache for PythonPrimEvaluator. Be careful that
 the infer function of PythonPrimitive in python code should
 be idempotent.

Merge pull request !41 from changzherui/syn-code

This reverts commit d447364417.

Merge pull request !390 from gukecai/master

Merge pull request !406 from Peilin/first-row-crc-check

addressed code review comments. added check in python layer to exclude directories and to raise an error if a pattern does not match any file

fixed clang format

fixed cppcheck

fixed cppcheck (used std::accumulate and std::copy_if). regenerated tfrecord file to contain correct header, it was a dummy header before

fixed cppcheck: added const reference for string parameter for lambdas, fixed clang format: whitespace adjustments

more clang whitespace fixes...

changed print to logger.info

Merge pull request !425 from yanghaitao/yht_textfiledatasetv2