* Add normalization operator.
1. Refine the raw norm_op and let it more general to support to normalize Tensor along any axis.
2. There is a bug in l2_normalize API, which lacks sqrt after `reduce_sum`.
3. Use norm_op to refine the l2_normalize API.
4. Fix bug in test_normalization_wrapper.py.

* Add slice op.

* Remove using from header file and fix doc.

* Fix doc

* Small fix.

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* "add inplace attribute"

* "register inplace attribute"

* "change se-next model for memory-reuse"

* "fix typo"

* repick

* fix merge conflict

* "fix stupid error"

replace use_event with use_cuda, because use_event means the program running with CUDA, so use_cuda maybe more intuitive.

* Remove unused arg_max/min_op.h
* Remove reference parameter. Use pointer insteaded.
* undef macro
* Always set OutT as int64_t.

* fix dist train error

* update by comment