* fix padding error

* add tensorflow based CopyRNN model, including training and predict …

…logic

* add fix_batch_size option during training

* fix inference output sentence order error

* continue implementing CopyCNN and CopyTransformer

update changelog

* fix beam search exception in CopyRNN

* fix beam search exception in CopyRNN

- fix github workflow push config

- fix requirement bug

- construct basic architecture of project

- implement CopyRNN (total available), CopyTransformer (required to debug)