软件工程实习作业：项目代码整改
- format code to match Python pep8 regulations
- fix countless typo
- project restructure: gather Models/Layers/DataProcess/others
- rename layers properly (e.g. MediumLayer -> StackingLayer)
- rename variables with reasonable names (e.g. in AttensionLayer: "a" -> enc_out; "y_trans" -> dec_out_transposed; "b" -> attension_score; etc.)
- remove unnecessary imports
- remove seeding in Layer definitions (we don't need random seeding there)
- define hyper params properly
- define paths in standalone file
- (more under-the-hood changes that I can't remember.......)