設定情報の保存の対応

	modified:   android/assets/neko.png
	modified:   core/src/com/zarudama/fishcatch/FishcatchGame.java
	modified:   core/src/com/zarudama/fishcatch/GameScreen.java
	modified:   core/src/com/zarudama/fishcatch/MainMenuScreen.java
	new file:   core/src/com/zarudama/fishcatch/Settings.java