implementation 99% complete

everything and tested except for repeatable shuffling

tested most basic/typical split usecases

cleanup

some more cleanup

fix CI

more ci fix

more ci fixes

more ci fix

more ci fix

more ci fix

added more tests, fixed some bugs

some more clean up and test cases

added shard/shuffle before split warning/error

addressed code review comments and ci

fixed ci

Merge pull request !1307 from cathwong/ckw_dataset_ut_unskip2

Merge pull request !1272 from JunhanHu/minddata_opt

-replace switch'case by indexing

- Add test case
- Add constructors
- Add getItem string

- Fix bugs
- Add more tests

- Tensor iterator
- asNumpy
- TextFileDataset

- Tensor(Numpy)

- Super > 2D
- Add more test cases for GeneratorDataset

- Change StartAddr to GetBuffer and GetMutableNuffer

- Raise an error if batch is used with strings

Clean-up work

Merge pull request !1157 from ms_yan/concat_dataset

Merge pull request !1126 from xiefangqi/voc_support_detection

change to use __add__ operation instead ds.concat

Merge pull request !984 from Tinazhang/hwc2chw

Merge pull request !960 from EricZ/grayscale_fix

Merge pull request !507 from ZiruiWu/batch_with_padding

Merge pull request !951 from guozhijian/fix_read_by_columns

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

Comparison example

Added md5 and comparison example for py_transforms

Added md5 check for images

Added testcase to show that c image aug don't use seed properly

Added passing test cases

Added working testcases for using seed

Added additional test cases to show seed use

Added test case for seed

Merge pull request !875 from AdelShafiei/ua_py

Merge pull request !872 from JunhanHu/generator_schema

Merge pull request !869 from JesseKLee/random_data_op

Merge pull request !672 from AdelShafiei/ua_ut

Merge pull request !603 from liyong126/update_pk_sampler

Merge pull request !671 from EricZ/master

Merge pull request !466 from h.farahat/deepcopy