improvements:

• parallel loading for faster startup time
• batch loading of library on startup for better user experience
• added shuffle mode
• added config file allowing users to configure colors and keybindings
• extensive refactoring of player management:
  • single persistent instance instead of creating new instances
  • simplified data handling in cursive::user_data for better maintainability

bugs:

• added build.rs to dynamically link homebrew-provided ncurses libraries on macOS (#13)