Librebook Versions Save

Changelog:

• Add download location feature
• Fix download list error #4
• Add dark mode
• Add localization
  • Indonesia 100%
  • German 90%
  • France 90%
  • China 90%
• Polish UI
  • Change UI primary color for better dark mode visibility
  • Change the font style so that it can follow the guidelines of Material Design 2.0