将操作说明拆分为独立游戏规则页面并精简主界面侧栏

src/include/Tetris.h

@@ -64,7 +64,8 @@ enum ScreenState
 {
     SCREEN_MENU = 0,
     SCREEN_PLAYING = 1,
-    SCREEN_UPGRADE = 2
+    SCREEN_UPGRADE = 2,
+    SCREEN_RULES = 3
 };
 
 enum GameMode
@@ -108,6 +109,7 @@ void ComputeTarget();
 void Restart();
 void StartGameWithMode(int mode);
 void ReturnToMainMenu();
+void OpenRulesScreen();
 void OpenUpgradeMenu();
 void ConfirmUpgradeSelection();