Changelogs:
- Removed a package from requirements.txt as it's no longer used.
- Removed some import libs from import_libs, as they are no longer used.
- Improved the Menu.py functions:
- Most of stuff are revised to use venv's python directly.
- Menu text is center now.
- Renamed palguard to paldefender.
- Renamed palguard_bases.py to paldefender_bases.py
- Updated README.md with new pic of menu.
