Release v2.0.0 - Leaderboard, Keyboard Navigation and Web

In this version, some important features are implemented such as leaderboard (Report page in game) which requires persistence storage, recording game-play data and taking screenshots; UI navigation by keyboard which is provided by bevy_ui_navigation; control/hyper max-chain challenges and web platform support (finally). The difficulty is also changed a lot (easier?) by adjusting particles' speed and amount. It's quite different from v1.0.0 (After all, only one week to make it at that time). Enjoy~