1. Thay doi cach loadFile va saveFile: OK
   Ghi va doc file bang doi tuong thay vi text
   
2. Update comment trong tat ca lib File : OK

3. Mot so thay doi khac
- Huy bo thao tac saveFile khi click nut Random
- Moi khi Add hoac Delete mon an thi se saveFile
- Random mon an khi click nut Random chu khong random san khi init() nua