Implement baseline

[chenzizhao]

• [x] download source data at https://github.com/SJTU-YONGFU-RESEARCH-GRP/SPRSound
• [x] split events
• [x] preprocess (according to the baseline) and save/pack
• [x] dataloader for other tasks 2-2, 1-1, 1-2
• [x] implement main.py
• [x] implement main.py for release
• [x] implement the baseline model from https://github.com/SJTU-YONGFU-RESEARCH-GRP/Lung-Sound-Classification-System-LungSys-I