Fixing bugs in UI animations, added credits

src/MenuManager.h

@@ -172,6 +172,7 @@ namespace ZL {
 		//void closePortraitJournalItemCompletely();
 
 		void showAboutScreen();
+		void showCreditsScreen();
 		void showSettingsScreen();
 		void showSettingsGraphicsScreen();
 		void showLanguageScreen();
@@ -262,6 +263,7 @@ namespace ZL {
 
 		std::shared_ptr<UiNode> mainMenuRoot;
 		std::shared_ptr<UiNode> aboutScreenRoot;
+		std::shared_ptr<UiNode> creditsScreenRoot;
 		std::shared_ptr<UiNode> settingsScreenRoot;
 		std::shared_ptr<UiNode> settingsGraphicsScreenRoot;
 		std::shared_ptr<UiNode> languageScreenRoot;