Added Distributed sampler option

Fix style

Merge pull request !3549 from anthonyaje/device_augment_mapop_refactor1

Merge pull request !3603 from jiangzhiwen/fix_column_names_exceeded

Refactored MapOp to in preparation to support device augment

Minor fix

Merge pull request !3551 from nhussain/fix_cpp_only_build

Merge pull request !3569 from xiefangqi/md_fix_flat_head

Merge pull request !3452 from nhussain/refactor_name_function

Merge pull request !2983 from h.farahat/tensor_class

Merge pull request !3395 from Alexey_Shevlyakov/remove_windows_define

- cleanup work on createTensor and Tensor's constructors

Merge pull request !3396 from panfengfeng/fix_getdataset_size_error

Merge pull request !3412 from qianlong21st/fix_cache

Merge pull request !3294 from nsyca/removal_pass

Merge pull request !3332 from jiangzhiwen/fix_csv_shard

Merge pull request !3248 from shenwei41/sw_master

Merge pull request !3232 from yanghaitao/yht_profiling_throughtout

Merge pull request !3093 from xiefangqi/md_voc_multi_columns

Merge pull request !3241 from panfengfeng/fix_some_log_error

Merge pull request !3212 from anzhengqi/epochs-ready